Samba Rsync

rsync 3.1.0-3.4.x DNS Bypass: Host Blocking Skipped on Lookup Failure
CVE-2026-70452 9.1 - Critical - August 13, 2026

rsync 3.1.0 before 3.5.0 contains an access control bypass vulnerability that allows remote attackers to circumvent hosts deny rules by inducing DNS resolution failures during hostname-based access control evaluation. When a DNS lookup for a hostname-based deny rule fails, the daemon skips the rule rather than defaulting to a deny decision, enabling attackers who can trigger DNS failures to bypass module-level IP access controls and gain unauthorized access to restricted module file trees.

AuthZ

rsync <3.5.0 DOS via hash_search algorithmic complexity
CVE-2026-70453 8.7 - High - August 13, 2026

rsync before 3.5.0 contains an algorithmic complexity vulnerability in the hash_search() function that allows a remote attacker to cause a denial of service by delivering a carefully constructed file list. A sender can exploit the quadratic-time worst-case behavior in hash lookups to exhaust receiver CPU resources with a modest number of crafted entries, causing a sustained denial of service.

Inefficient Algorithmic Complexity

rsync TLS Cert Validation Fails 3.2.03.2.3, 3.4.4 (OpenSSL/Stunnel)
CVE-2026-70454 7.6 - High - August 13, 2026

rsync 3.2.0 through 3.2.3 (openssl mode) and rsync-ssl through 3.4.4 (stunnel mode) contain a TLS certificate validation vulnerability that allows on-path attackers to intercept encrypted sessions by presenting self-signed or otherwise invalid certificates. Attackers can exploit the failure to validate server TLS certificates against a trusted CA or verify certificate hostname matching to decrypt or tamper with rsync session content without detection by the client.

Improper Certificate Validation

rsync 3.4.2<3.5.0 DDoS via --zt Zstd thread abuse
CVE-2026-70455 8.7 - High - August 13, 2026

rsync 3.4.2 before 3.5.0 contains a denial of service vulnerability that allows a remote sender to exhaust system resources by specifying the --zt short alias for --compress-threads, which bypasses the refuse options directive's string matching on long option names. Attackers can specify --zt=N with a large value to spawn an unbounded number of Zstandard worker threads on the receiver, exhausting available thread and memory resources.

Allocation of Resources Without Limits or Throttling

rsync OOB Write in read_args() 3.0.1<3.5.0
CVE-2026-70456 8.8 - High - August 13, 2026

rsync 3.0.1 before 3.5.0 contains an out-of-bounds write vulnerability in the read_args() function that allows a malicious sender to corrupt adjacent heap memory by sending a crafted argument list. When the argument count causes the argv allocation to be exactly full, the trailing NULL terminator is written one slot beyond the allocation boundary, corrupting adjacent heap memory.

Memory Corruption

rsync 3.x OOB write in parse_size_arg before 3.5.0
CVE-2026-70457 8.3 - High - August 13, 2026

rsync 3.2.3 before 3.5.0 contains an out-of-bounds write in parse_size_arg() where the return value of snprintf() is used directly as an index into a .bss-segment array without bounds checking. When snprintf truncates the formatted size string, the return value equals the number of characters that would have been written including the truncated portion, and this value may exceed the array length. The subsequent indexed write targets memory outside the intended array bounds, corrupting .bss memory.

Incorrect Calculation of Buffer Size

rsync <3.5.0: OOB Write via HLINK_BUMP (missing F_SUM)
CVE-2026-70458 8.8 - High - August 13, 2026

rsync 3.0.0 before 3.5.0 contains an out-of-bounds write vulnerability that allows attackers to corrupt memory by triggering HLINK_BUMP processing on file entries with the FLAG_HLINKED flag set while the hard-link preservation option is inactive. Attackers can exploit the missing F_SUM field in the file_struct layout to access memory past the end of the allocated structure, corrupting adjacent heap or stack data.

Memory Corruption

rsync <3.5.0 Null Pointer Deref in child daemon via dot entry
CVE-2026-70459 6.9 - Medium - August 13, 2026

rsync 3.0.0 before 3.5.0 contains a null pointer dereference vulnerability in the daemon child process that allows remote attackers to crash the daemon by sending a file list whose first entry is a dot entry not typed as a directory. The daemon dereferences the first file list entry as a directory structure pointer without verifying the entry type, resulting in an invalid or uninitialized pointer dereference that terminates the client connection.

Use of Uninitialized Resource

rsync 2.3.3-3.5.0 Path Traversal via --partial-dir/--backup-dir symlinks
CVE-2026-70460 9.2 - Critical - August 13, 2026

rsync 2.3.3 before 3.5.0 contains a path traversal vulnerability that allows a malicious sender to escape the module root by exploiting symlinks within the module file tree when using --partial-dir or --backup-dir options. Attackers with write access to place a symlink under the module root, or who can exploit a pre-existing trusted symlink, can direct file writes to locations outside the intended module root, achieving arbitrary file write relative to the module root parent.

Directory traversal

Rsync 3.2.53.4.9: Heap OOB Write via files-from
CVE-2026-70461 8.8 - High - August 13, 2026

rsync 3.2.5 before 3.5.0 contains a heap out-of-bounds write vulnerability that allows remote unauthenticated attackers to write one attacker-controlled byte past the end of a heap allocation by supplying a crafted files-from entry. Attackers can trigger the vulnerability against a read-only rsync daemon module by providing a files-from entry containing both an interior and trailing backslash, causing the add_implied_include() function to under-count the trailing backslash when sizing the destination buffer.

Memory Corruption

Signed Int Overflow in rsync 3.1.0-<3.5.0 I/O Timeout Resource Exhaustion
CVE-2026-70462 7.1 - High - August 13, 2026

rsync 3.1.0 before 3.5.0 contains a signed integer overflow vulnerability in the I/O timeout implementation that allows attackers to permanently disable connection timeouts by injecting MSG_IO_TIMEOUT messages carrying non-positive (zero or negative) values. Attackers can craft malicious MSG_IO_TIMEOUT messages that cause the timeout variable to wrap to a non-positive value, preventing the timeout check from firing and enabling idle or stalled connections to hold daemon slots indefinitely, leading to resource exhaustion.

Integer Overflow or Wraparound

rsync 3.1.0-3.4.x Auth Users Bypass via @Group Name Parsing
CVE-2026-70463 8.6 - High - August 13, 2026

rsync 3.1.0 before 3.5.0 contains an authorization bypass in auth users directive parsing. The auth users parser uses comma-only tokenization when splitting the user list, which fails to correctly handle entries of the form @Group Name where the group name contains a space. The space within the group name causes the parser to split the entry at the space boundary, discarding the deny rule associated with the group. An authenticated user whose username or group membership would be denied by an @Group Name auth users entry can connect to a restricted module because the deny rule is silently discarded during parsing.

AuthZ

DoS via connection slot exhaustion in rsync 2.0.03.5.0
CVE-2026-70464 8.7 - High - August 13, 2026

rsync daemon 2.0.0 before 3.5.0 contains a denial of service vulnerability that allows unauthenticated remote attackers to exhaust daemon connection slots by stalling the handshake process before or after module selection without triggering the I/O timeout. Attackers can open many simultaneous connections and trickle data at the minimum rate to avoid timeout, or stall entirely before module selection where no timeout applies, consuming all available connection slots and denying service to legitimate clients.

Allocation of Resources Without Limits or Throttling

rsync <3.5.0 Symlink Race in Sender Directory Scanning
CVE-2026-53801 8.2 - High - August 13, 2026

rsync before 3.5.0 contains a symlink race condition vulnerability in the sender's directory scanning logic that allows attackers to cause the sender to enumerate and transfer files outside the module root's intended subtree. Attackers who can create or manipulate symlinks in a path component of the scanned tree can replace a symlink with a directory entry pointing outside the module root between the lstat() call and the subsequent opendir() call, exposing files beyond the intended root in both daemon-mode and non-daemon sender-side scanning.

insecure temporary file

rsync <=3.5.0 symlink race in --remove-source-files cause arbitrary file deletion
CVE-2026-53800 5.7 - Medium - August 13, 2026

rsync before 3.5.0 contains a symlink race condition vulnerability in the --remove-source-files feature that allows attackers with symlink creation access to cause arbitrary file deletion. Attackers can atomically substitute a symlink for a source file between transfer completion and the unlink() call, causing rsync to delete the symlink target rather than the intended source file.

insecure temporary file

Rsync <3.5.0 Symlink Race Condition Enables Local Privilege Escalation
CVE-2026-53799 7.2 - High - August 13, 2026

rsync before 3.5.0 contains a symlink race condition vulnerability that allows local attackers to cause rsync to apply arbitrary ACLs or extended attributes to unintended files by substituting a symlink at a predictable destination path between the file write and the subsequent acl_set_file() or lsetxattr() call. Attackers can exploit this timing window to redirect ACL and xattr application through a crafted symlink to files outside the intended destination tree, potentially granting elevated permissions and enabling local privilege escalation.

insecure temporary file

rsync <3.5.0 Symlink Race: File Disclosure via Parent Directory Manipulation
CVE-2026-53797 5.7 - Medium - August 13, 2026

rsync before 3.5.0 contains a symlink race condition vulnerability in the sender's source tree traversal that allows an attacker who can manipulate a parent directory of the source tree to redirect file reads to unintended paths. Attackers can atomically replace a parent directory component with a symlink pointing outside the source root between path resolution and file open operations to disclose file contents outside the intended transfer root.

insecure temporary file

rsync<3.5.0 TOCTOU in nondaemon receiver destdir handling
CVE-2026-53796 5.8 - Medium - August 13, 2026

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the non-daemon receiver's destination directory handling that allows an attacker who can manipulate destination path parent components to redirect file writes to unintended locations. Attackers can substitute a symlink for a component of the destination path between the path resolution and chdir() call, causing the receiver's working directory to be established outside the intended destination tree so that subsequent relative-path file writes land in unintended filesystem locations.

insecure temporary file

rsync <3.5.0 Arbitrary File Write via --temp-dir / --link-dest (Rename Bypass)
CVE-2026-53795 7.2 - High - August 13, 2026

rsync before 3.5.0 contains an arbitrary file write vulnerability that allows attackers to write files outside the intended destination tree by specifying an absolute path via --temp-dir or --link-dest options. The rename-confinement logic is bypassed when these options resolve to paths outside the destination tree, enabling attacker-controlled values to write files to arbitrary locations accessible to the rsync process.

insecure temporary file

rsync <3.5.0 --max-alloc Logic Error Enables Unlimited Allocation & DoS
CVE-2026-53794 6.9 - Medium - August 13, 2026

rsync before 3.5.0 contains a logic error in --max-alloc handling that allows a sender or configuration setting --max-alloc=0 to disable allocation sanity checks entirely rather than enforcing a zero-byte cap. Attackers can exploit this flaw to cause the receiver to attempt unbounded memory allocations for file list and data structures, potentially exhausting available memory and causing a denial of service.

Improper Validation of Specified Quantity in Input

rsync <3.5.0 Path Confinement Bypass via /./ Module Root Marker
CVE-2026-53793 9.1 - Critical - August 13, 2026

rsync before 3.5.0 contains a path confinement bypass vulnerability that allows remote clients to escape the intended inner-module root confinement by constructing paths that resolve outside the chroot boundary when the module root contains a /./ boundary marker. Attackers can exploit improper handling of the /./ notation or forge delta-basis transfers referencing xname paths that cross the /./ boundary to gain unauthorized read or write access to files outside the module's subtree.

insecure temporary file

Rsync <3.5.0 OOB Read via Zero-Checksum Block
CVE-2026-53792 7.1 - High - August 13, 2026

rsync before 3.5.0 contains an out-of-bounds read vulnerability in the sender-side block matching logic that allows a malicious receiver to trigger memory access before the start of an allocated buffer by sending a crafted checksum block with a length of zero. Attackers can send a specially crafted checksum set containing a zero-length block to cause a negative offset calculation during delta computation, resulting in an out-of-bounds read of file data buffer memory on the sender side.

out-of-bounds array index

IP Spoofing via PROXY header in rsync daemon <3.5.0
CVE-2026-53791 9.1 - Critical - August 13, 2026

rsync daemon before 3.5.0 contains an IP address spoofing vulnerability that allows unauthenticated remote attackers to bypass IP-based access controls by sending a crafted PROXY protocol header with a forged source address. Attackers who can connect directly to the rsync daemon can inject a spoofed source IP in the PROXY protocol header to circumvent hosts allow/deny rules, gaining unauthorized access that would otherwise be blocked based on their real source address.

Authentication Bypass by Spoofing

rsync <3.5.0 Command & Argument Injection via ENV & Hooks
CVE-2026-53790 9.2 - Critical - August 13, 2026

rsync before 3.5.0 contains multiple command and argument injection vulnerabilities that allow attackers to execute arbitrary commands by supplying malicious input through several code paths, including the RSYNC_CONNECT_PROG environment variable, daemon hooks, the rsync-ssl wrapper, and remote-shell command newline injection. Attackers can inject shell metacharacters or newline characters into unsanitized user-supplied values such as hostnames and hostspecs to execute arbitrary commands under the privileges of the rsync process or the invoking user.

Shell injection

rsync 3.5.0 Improper Path Handling in --delete (CVE-2026-53789)
CVE-2026-53789 7.1 - High - August 13, 2026

rsync before 3.5.0 contains an improper path handling vulnerability that allows a malicious sender to expand the scope of --delete operations beyond the intended destination subtree by sending a crafted file list that causes rsync to reclassify implied parent directory entries or treat synthetic paths as the transfer root. Attackers can exploit multiple variants including implied parent reclassification, synthetic root path construction, legacy protocol behavior below version 30, and non-directory root handling to cause the receiver to delete files outside the authorized destination directory.

Reliance on Untrusted Inputs in a Security Decision

rsync <=3.5.0 Newline Injection in Name-Converter UID/GID Mapping
CVE-2026-53788 6.9 - Medium - August 13, 2026

rsync before 3.5.0 contains a newline injection vulnerability in the name-converter uid/gid mapping interface that allows local attackers to forge protocol messages by creating user or group names containing newline characters. Attackers can inject malicious newline characters into names communicated over the pipe-based line-oriented protocol to cause the rsync daemon to process attacker-influenced data as legitimate protocol input, corrupting uid/gid mapping logic.

CRLF Injection

Rsync pre-3.5.0 Priv Conf in name-conv uid/gid mapping root file ownership
CVE-2026-53798 6.9 - Medium - August 13, 2026

rsync before 3.5.0 contains a privilege confusion vulnerability in the name-converter subprocess uid/gid mapping that allows local attackers to cause transferred files to be owned by root by influencing name-converter responses to return empty values. When the name-converter subprocess returns an empty response for a uid or gid lookup, rsync incorrectly interprets it as a successful resolution to uid/gid 0 (root) rather than a lookup failure, and if the name-converter also signals fake super-user status, rsync proceeds with root ownership assignments for transferred files.

Incorrect Type Conversion or Cast

rsync <3.5.0 Filter Bypass via --filter Merge File Directives
CVE-2026-53786 6.9 - Medium - August 13, 2026

rsync before 3.5.0 contains a filter rule bypass vulnerability that allows authenticated clients to override module-level filter restrictions by supplying malicious --filter merge file directives. Attackers can inject client-side merge file directives during filter evaluation to introduce rules that supersede daemon module-level restrictions, gaining access to files the module filter was intended to exclude.

AuthZ

Rsync 3.5.0 Path Traversal via Symlink in --relative Mode
CVE-2026-53785 6.9 - Medium - August 13, 2026

rsync before 3.5.0 contains a path traversal vulnerability that allows a malicious sender to write files outside the intended destination directory tree by crafting relative paths with symlink components in --relative mode. The make_path() function follows symlinks pointing outside the destination tree while creating intermediate directories without verifying that created paths remain within the destination boundary, enabling arbitrary file writes on the receiver's filesystem.

insecure temporary file

RSync Path Traversal via Symlinked Module Root (<3.5.0)
CVE-2026-53784 8.4 - High - August 13, 2026

rsync before 3.5.0 contains a path traversal vulnerability that allows remote clients to access files outside the intended module root when use chroot is disabled and the module root path or a component of it is a symlink. The daemon calls chdir() to the module root at session initialization without resolving symlinks via realpath() or equivalent, causing subsequent relative-path operations to reference files relative to the symlink target rather than the intended module root, enabling unauthorized file access.

insecure temporary file

rsync 3.5.0 rrsync TOCTOU: symlink escape & unsafe flag abuse
CVE-2026-53783 8.6 - High - August 13, 2026

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.

insecure temporary file

rsync <3.5.0 Symlink Following Allows Local Privilege Escalation
CVE-2026-53803 8.5 - High - August 13, 2026

rsync before 3.5.0 contains a symlink following vulnerability that allows local attackers to overwrite arbitrary files by placing a symlink at a predictable output path such as --log-file, --write-batch, or daemon-mode log and statistics paths. Attackers can exploit rsync's failure to reject symlinks during ancillary file writes to redirect output to arbitrary filesystem locations, achieving local privilege escalation on installations where rsync runs with elevated privileges such as setuid or privileged daemon configurations.

insecure temporary file

Arbitrary File Read in rsync <3.5.0 via symlink handling
CVE-2026-53802 8.4 - High - August 13, 2026

rsync before 3.5.0 contains an arbitrary file read vulnerability that allows attackers to read files accessible to the rsync daemon process by exploiting symlink following in input configuration file handling including --files-from, --password-file, and filter merge files. Attackers can place a symlink at a predictable --files-from or --password-file path, or supply a --files-from path that escapes the daemon module root, to read arbitrary files accessible to the rsync process.

Symlink following

Rsync <=3.4.3 TOCTOU Race Allows Arbitrary File Write/Privilege Escalation
CVE-2026-29518 7.8 - High - May 20, 2026

Rsync versions before 3.4.3 contain a time-of-check to time-of-use (TOCTOU) race condition in daemon file handling that allows attackers to redirect file writes outside intended directories by replacing parent directory components with symbolic links. Attackers with write access to a module path can exploit this race condition to create or overwrite arbitrary files, potentially modifying sensitive system files and achieving privilege escalation when the daemon runs with elevated privileges. This vulnerability can only be triggered if the chroot setting is false.

TOCTTOU

Rsync Hostname-based ACL bypass <3.4.3: Auth bypass via PTR
CVE-2026-43617 4.8 - Medium - May 20, 2026

Rsync version 3.4.2 and prior contain an authorization bypass vulnerability in the rsync daemon's hostname-based access control list enforcement when configured with chroot. Attackers can bypass hostname-based deny rules by controlling the PTR record for their source IP address, allowing connections from hostnames that administrators intended to deny when reverse DNS resolution fails and defaults to UNKNOWN.

Authentication Bypass by Alternate Name

Rsync 3.4.2 and earlier Integer Overflow in compressed-token decoder
CVE-2026-43618 8.1 - High - May 20, 2026

Rsync version 3.4.2 and prior contain an integer overflow vulnerability in the compressed-token decoder where a 32-bit signed counter is not checked for overflow, allowing a malicious sender to trigger an overflow that causes the receiver process to read and return data from outside the intended buffer bounds. Attackers can exploit this vulnerability to disclose process memory contents including environment variables, passwords, heap and stack data, and library memory pointers, significantly reducing ASLR effectiveness and facilitating further exploitation.

Integer Overflow or Wraparound

rsync 3.4.2 and earlier Symlink Race Condition in Path-based Syscalls
CVE-2026-43619 6.3 - Medium - May 20, 2026

Rsync version 3.4.2 and prior contain symlink race condition vulnerabilities in path-based system calls including chmod, lchown, utimes, rename, unlink, mkdir, symlink, mknod, link, rmdir, and lstat that allow local attackers to redirect operations to files outside the exported rsync module. Attackers with local filesystem access can exploit the timing window between path resolution and syscall execution by swapping symlinks to apply sender-supplied permissions, ownership, timestamps, or filenames to arbitrary files outside the intended module boundary on rsync daemons configured with 'use chroot = no'.

TOCTTOU

Rsync <3.4.3: Receiver-side OOB array read crash via CF_INC_RECURSE
CVE-2026-43620 6.5 - Medium - May 20, 2026

Rsync version 3.4.2 and prior contain a receiver-side out-of-bounds array read vulnerability in recv_files() in receiver.c that allows a malicious rsync server to crash the rsync client process. Attackers can exploit the vulnerability by setting CF_INC_RECURSE in compatibility flags and sending a specially crafted file list where the first sorted entry is not the leading dot directory, followed by a transfer record with ndx=0 and an iflag word without ITEM_TRANSFER, causing the receiver to read 8 bytes before the allocated pointer array and dereference an invalid pointer at an unmapped address, resulting in a deterministic SIGSEGV crash of the rsync client.

Out-of-bounds Read

Rsync <3.4.3: OOB stack write in establish_proxy_connection()
CVE-2026-45232 3.1 - Low - May 20, 2026

Rsync versions before 3.4.3 contain an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function in socket.c that allows network attackers to corrupt stack memory by sending a malformed HTTP proxy response. Attackers can exploit this by positioning themselves between the client and proxy or controlling the proxy server to send a response line of 1023 or more bytes without a newline terminator, causing a null byte to be written to an out-of-bounds stack address when the RSYNC_PROXY environment variable is set.

off-by-five

rsync 3.0.13.4.1 Receiver UAF in receive_xattr (qsort untrusted len)
CVE-2026-41035 7.4 - High - April 16, 2026

In rsync 3.0.1 through 3.4.1, receive_xattr relies on an untrusted length value during a qsort call, leading to a receiver use-after-free. The victim must run rsync with -X (aka --xattrs). On Linux, many (but not all) common configurations are vulnerable. Non-Linux platforms are more widely vulnerable.

length manipulation

rsync Daemon Heap Bof via Checksum Length Overrun
CVE-2024-12084 9.8 - Critical - January 15, 2025

A heap-based buffer overflow flaw was found in the rsync daemon. This issue is due to improper handling of attacker-controlled checksum lengths (s2length) in the code. When MAX_DIGEST_LEN exceeds the fixed SUM_LENGTH (16 bytes), an attacker can write out of bounds in the sum2 buffer.

Heap-based Buffer Overflow

Rsync: Checksum Length Manipulation Enables Stack Data Leak
CVE-2024-12085 7.5 - High - January 14, 2025

A flaw was found in rsync which could be triggered when rsync compares file checksums. This flaw allows an attacker to manipulate the checksum length (s2length) to cause a comparison between a checksum and uninitialized memory and leak one byte of uninitialized stack data at a time.

Use of Uninitialized Resource

Rsync --safe-links Path Traversal, Arbitrary File Write
CVE-2024-12088 6.5 - Medium - January 14, 2025

A flaw was found in rsync. When using the `--safe-links` option, the rsync client fails to properly verify if a symbolic link destination sent from the server contains another symbolic link within it. This results in a path traversal vulnerability, which may lead to arbitrary file write outside the desired directory.

Directory traversal

Path traversal in rsync via --inc-recursive option
CVE-2024-12087 6.5 - Medium - January 14, 2025

A path traversal vulnerability exists in rsync. It stems from behavior enabled by the `--inc-recursive` option, a default-enabled option for many client options and can be enabled by the server even if not explicitly enabled by the client. When using the `--inc-recursive` option, a lack of proper symlink verification coupled with deduplication checks occurring on a per-file-list basis could allow a server to write files outside of the client's intended destination directory. A malicious server could write malicious files to arbitrary locations named after valid directories/paths on the client.

Directory traversal

Rsync Server Remote File Enumeration via Checksum Exploit
CVE-2024-12086 6.1 - Medium - January 14, 2025

A flaw was found in rsync. It could allow a server to enumerate the contents of an arbitrary file from the client's machine. This issue occurs when files are being copied from a client to a server. During this process, the rsync server will send checksums of local data to the client to compare with in order to determine what data needs to be sent to the server. By sending specially constructed checksum values for arbitrary files, an attacker may be able to reconstruct the data of those files byte-by-byte based on the responses from the client.

Detection of Error Condition Without Action

Rsync <3.2.5 Remote File Overwrite via Client Name Validation Bypass
CVE-2022-29154 7.4 - High - August 02, 2022

An issue was discovered in rsync before 3.2.5 that allows malicious remote servers to write arbitrary files inside the directories of connecting peers. The server chooses which files/directories are sent to the client. However, the rsync client performs insufficient validation of file names. A malicious rsync server (or Man-in-The-Middle attacker) can overwrite arbitrary files in the rsync client target directory and subdirectories (for example, overwrite the .ssh/authorized_keys file).

Improper Input Validation

A flaw was found in rsync in versions since 3.2.0pre1
CVE-2020-14387 7.4 - High - May 27, 2021

A flaw was found in rsync in versions since 3.2.0pre1. Rsync improperly validates certificate with host mismatch vulnerability. A remote, unauthenticated attacker could exploit the flaw by performing a man-in-the-middle attack using a valid certificate for another hostname which could compromise confidentiality and integrity of data transmitted using rsync-ssl. The highest threat from this vulnerability is to data confidentiality and integrity. This flaw affects rsync versions before 3.2.4.

Improper Validation of Certificate with Host Mismatch

The parse_arguments function in options.c in rsyncd in rsync before 3.1.3 does not prevent multiple --protect-args uses, which
CVE-2018-5764 7.5 - High - January 17, 2018

The parse_arguments function in options.c in rsyncd in rsync before 3.1.3 does not prevent multiple --protect-args uses, which allows remote attackers to bypass an argument-sanitization protection mechanism.

rsync 3.1.1 allows remote attackers to write to arbitrary files
CVE-2014-9512 - February 12, 2015

rsync 3.1.1 allows remote attackers to write to arbitrary files via a symlink attack on a file in the synchronization path.

insecure temporary file

rsync 3.x before 3.0.8, when certain recursion, deletion, and ownership options are used
CVE-2011-1097 - March 30, 2011

rsync 3.x before 3.0.8, when certain recursion, deletion, and ownership options are used, allows remote rsync servers to cause a denial of service (heap memory corruption and application crash) or possibly execute arbitrary code via malformed data.

Buffer Overflow