Exim

Exim <4.100.1 SMTP Smuggling via DATA Rejection
CVE-2026-94057 4 - Medium - September 19, 2026

Exim before 4.100.1 allows SMTP smuggling in which the received message does not match any sent message, and instead depends on crafted data sent after a rejection during DATA processing.

CRLF Injection

Exim <4.100.1: Proxy-Protocol Uninit Stack Data Leak
CVE-2026-94056 7.5 - High - September 19, 2026

Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, allows attackers to read certain uninitialized data from stack memory.

Use of Uninitialized Resource

Exim <4.100.1 Use-After-Free via GnuTLS TLS Settings
CVE-2026-94055 3.7 - Low - September 19, 2026

Exim before 4.100.1, when certain non-default TLS settings are used with GnuTLS, has a use-after-free.

Dangling pointer

Exim <4.100.1 OOB Write via Proxy-Protocol (attacker-controlled IP)
CVE-2026-94054 7 - High - September 19, 2026

Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, has an out-of-bounds write.

Memory Corruption

Exim <4.99.5 .forward Priv Escalation via Pipe Force_Command Mishandling
CVE-2026-66141 7.4 - High - July 24, 2026

Exim before 4.99.5 allows .forward privilege escalation because force_command for a pipe transport is mishandled.

Inclusion of Functionality from Untrusted Control Sphere

Exim <4.99.5 Directory Traversal via Queue-Name args
CVE-2026-66140 8.4 - High - July 24, 2026

Exim before 4.99.5 allows directory traversal to access files outside of the spool area, and consequently gain privileges, because arguments related to queue-name are mishandled.

Path Traversal: '../filedir'

Exim 4.88-4.99.4 Proxy bug discloses uninit stack memory
CVE-2026-48840 5.3 - Medium - May 30, 2026

Exim 4.88 before 4.99.4, in some proxy configurations, mishandles certain short payloads, leading to disclosure of uninitialized stack memory values to a client.

Signed comparison

Exim <4.99.3 Use-After-Free in BDAT body parsing via TLS close_notify
CVE-2026-45185 9.8 - Critical - May 12, 2026

Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body parsing path. It is triggered when a client sends a TLS close_notify mid-body during a CHUNKING transfer, followed by a final cleartext byte on the same TCP connection. This can lead to heap corruption. An unauthenticated network attacker exploiting this vulnerability could execute arbitrary code.

Dangling pointer

Exim <4.99.2 SPA Auth OOB Write & Data Leak
CVE-2026-40687 4.8 - Medium - April 30, 2026

In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory.

Missing Initialization of Resource

Exim <4.99.2 UTF-8 OOB Read with large trailing chars
CVE-2026-40686 3.7 - Low - April 30, 2026

In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.

Out-of-bounds Read

Exim <4.99.2 Heap OOB in JSON Lookup due to Malformed Header
CVE-2026-40685 6.5 - Medium - April 30, 2026

In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \ skipping.

Incorrect Provision of Specified Functionality

Exim <=4.99.1 Crash on musl via malformed DNS PTR (dn_expand)
CVE-2026-40684 5.9 - Medium - April 30, 2026

In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.

Incorrect Provision of Specified Functionality

Exim <4.99.1 Remote Heap Corruption
CVE-2025-67896 7 - High - December 14, 2025

Exim before 4.99.1, with certain non-default rate-limit configurations, allows a remote heap-based buffer overflow because database records are cast directly to internal structures without validation.

Heap-based Buffer Overflow

Exim logrotate Symlink Following P8 Escalation before 4.98.2
CVE-2025-53881 - October 02, 2025

A UNIX Symbolic Link (Symlink) Following vulnerability in logrotate config in the exim package allowed privilege escalation from mail user/group to root.This issue affects Tumbleweed: from ? before 4.98.2-lp156.248.1.

Symlink following

Use-After-Free in Exim 4.96-4.98.1 Allows Privilege Escalation
CVE-2025-30232 - March 28, 2025

A use-after-free in Exim 4.96 through 4.98.1 could allow users (with command-line access) to escalate privileges.

Exim 4.98<4.98.1 Remote SQLi via SQLite Hints & ETRN
CVE-2025-26794 7.5 - High - February 21, 2025

Exim 4.98 before 4.98.1, when SQLite hints and ETRN serialization are used, allows remote SQL injection. (Resolving SQL injection requires an update to 4.99.1 in certain non-default rate-limit configurations.)

SQL Injection

Exim <=4.97.1 RFC2231 Header Filename Parsing Bypass Allows Exec Attachments
CVE-2024-39929 - July 04, 2024

Exim through 4.97.1 misparses a multiline RFC 2231 header filename, and thus remote attackers can bypass a $mime_filename extension-blocking protection mechanism, and potentially deliver executable attachments to the mailboxes of end users.

Exim AUTH OOB Write RCE Vulnerability
CVE-2023-42115 - May 03, 2024

Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of a buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17434.

Exim SMTP NTLM Challenge Stack Buffer Overflow RCE
CVE-2023-42116 - May 03, 2024

Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17515.

Stack Overflow

Exim SMTP RCE: Improper Neutralization Leads to Remote Execution
CVE-2023-42117 - May 03, 2024

Exim Improper Neutralization of Special Elements Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-17554.

Improper Neutralization of Special Elements

Exim dnsdb OOB Read Info Disclosure in SMTP Service
CVE-2023-42119 - May 03, 2024

Exim dnsdb Out-Of-Bounds Read Information Disclosure Vulnerability. This vulnerability allows network-adjacent attackers to disclose sensitive information on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated buffer. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of the service account. . Was ZDI-CAN-17643.

Out-of-bounds Read

Exim NTLM Challenge OOB Read Info Disclosure
CVE-2023-42114 - May 03, 2024

Exim NTLM Challenge Out-Of-Bounds Read Information Disclosure Vulnerability. This vulnerability allows remote attackers to disclose sensitive information on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of NTLM challenge requests. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated data structure. An attacker can leverage this vulnerability to disclose information in the context of the service account. . Was ZDI-CAN-17433.

Out-of-bounds Read

Exim <4.97.1: SMTP Smuggling bypass SPF via PIPELINING/CHUNKING
CVE-2023-51766 - December 24, 2023

Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.

Exim DMARC Handler use-after-free in dmarc_dns_lookup
CVE-2022-3620 9.8 - Critical - October 20, 2022

A vulnerability was found in Exim and classified as problematic. This issue affects the function dmarc_dns_lookup of the file dmarc.c of the component DMARC Handler. The manipulation leads to use after free. The attack may be initiated remotely. The name of the patch is 12fb3842f81bcbd4a4519d5728f2d7e0e3ca1445. It is recommended to apply a patch to fix this issue. The associated identifier of this vulnerability is VDB-211919.

Buffer Overflow

Exim RegexHandler UAF in Regex Processing
CVE-2022-3559 4.6 - Medium - October 17, 2022

A vulnerability was found in Exim and classified as problematic. This issue affects some unknown processing of the component Regex Handler. The manipulation leads to use after free. The name of the patch is 4e9ed49f8f12eb331b29bd5b6dc3693c520fddc2. It is recommended to apply a patch to fix this issue. The identifier VDB-211073 was assigned to this vulnerability.

Buffer Overflow

Exim <4.95 Heap Buffer Overflow in host_name_lookup (alias list)
CVE-2022-37452 9.8 - Critical - August 07, 2022

Exim before 4.95 has a heap-based buffer overflow for the alias list in host_name_lookup in host.c when sender_host_name is set.

Memory Corruption

Exim <4.96: Invalid Free in pam_converse (store_free missing)
CVE-2022-37451 7.5 - High - August 06, 2022

Exim before 4.96 has an invalid free in pam_converse in auths/call_pam.c because store_free is not used after store_malloc.

Release of Invalid Pointer or Reference

The STARTTLS feature in Exim through 4.94.2
CVE-2021-38371 - August 10, 2021

The STARTTLS feature in Exim through 4.94.2 allows response injection (buffering) during MTA SMTP sending.

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges
CVE-2020-28007 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the log directory (owned by a non-root user), a symlink or hard link attack allows overwriting critical root-owned files anywhere on the filesystem.

insecure temporary file

Exim 4 before 4.94.2 has Execution with Unnecessary Privileges
CVE-2021-27216 6.3 - Medium - May 06, 2021

Exim 4 before 4.94.2 has Execution with Unnecessary Privileges. By leveraging a delete_pid_file race condition, a local user can delete arbitrary files as root. This involves the -oP and -oPX options.

Improper Privilege Management

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges
CVE-2020-28008 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the spool directory (owned by a non-root user), an attacker can write to a /var/spool/exim4/input spool header file, in which a crafted recipient address can indirectly lead to command execution.

Improper Privilege Management

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, relevant in non-default configurations
CVE-2020-28026 9.8 - Critical - May 06, 2021

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, relevant in non-default configurations that enable Delivery Status Notification (DSN). Certain uses of ORCPT= can place a newline into a spool header file, and indirectly allow unauthenticated remote attackers to execute arbitrary commands as root.

Exim 4 before 4.94.2
CVE-2020-28025 7.5 - High - May 06, 2021

Exim 4 before 4.94.2 allows Out-of-bounds Read because pdkim_finish_bodyhash does not validate the relationship between sig->bodyhash.len and b->bh.len; thus, a crafted DKIM-Signature header might lead to a leak of sensitive information from process memory.

Out-of-bounds Read

Exim 4 before 4.94.2 allows Buffer Underwrite
CVE-2020-28024 9.8 - Critical - May 06, 2021

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smtp_ungetc was only intended to push back characters, but can actually push back non-character error codes such as EOF.

Buffer Overflow

Exim 4 before 4.94.2 allows Out-of-bounds Read
CVE-2020-28023 7.5 - High - May 06, 2021

Exim 4 before 4.94.2 allows Out-of-bounds Read. smtp_setup_msg may disclose sensitive information from process memory to an unauthenticated SMTP client.

Out-of-bounds Read

Exim 4 before 4.94.2 has Improper Restriction of Write Operations within the Bounds of a Memory Buffer
CVE-2020-28022 9.8 - Critical - May 06, 2021

Exim 4 before 4.94.2 has Improper Restriction of Write Operations within the Bounds of a Memory Buffer. This occurs when processing name=value pairs within MAIL FROM and RCPT TO commands.

Buffer Overflow

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters
CVE-2020-28021 8.8 - High - May 06, 2021

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters. An authenticated remote SMTP client can insert newline characters into a spool file (which indirectly leads to remote code execution as root) via AUTH= in a MAIL FROM command.

Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in
CVE-2020-28020 9.8 - Critical - May 06, 2021

Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.

Integer Overflow or Wraparound

Exim 4 before 4.94.2 has Improper Initialization that can lead to recursion-based stack consumption or other consequences
CVE-2020-28019 7.5 - High - May 06, 2021

Exim 4 before 4.94.2 has Improper Initialization that can lead to recursion-based stack consumption or other consequences. This occurs because use of certain getc functions is mishandled when a client uses BDAT instead of DATA.

Improper Initialization

Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations
CVE-2020-28018 9.8 - Critical - May 06, 2021

Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.

Dangling pointer

Exim 4 before 4.94.2
CVE-2020-28016 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows an off-by-two Out-of-bounds Write because "-F ''" is mishandled by parse_fix_phrase.

Memory Corruption

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters
CVE-2020-28015 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters. Local users can alter the behavior of root processes because a recipient address can have a newline character.

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges
CVE-2020-28014 6.1 - Medium - May 06, 2021

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. The -oP option is available to the exim user, and allows a denial of service because root-owned files can be overwritten.

Improper Privilege Management

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow because it mishandles "-F '
CVE-2020-28013 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow because it mishandles "-F '.('" on the command line, and thus may allow privilege escalation from any user to root. This occurs because of the interpretation of negative sizes in strncpy.

Memory Corruption

Exim 4 before 4.94.2 allows Exposure of File Descriptor to Unintended Control Sphere because rda_interpret uses a privileged pipe
CVE-2020-28012 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Exposure of File Descriptor to Unintended Control Sphere because rda_interpret uses a privileged pipe that lacks a close-on-exec flag.

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S
CVE-2020-28011 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S. This may cause privilege escalation from exim to root.

Memory Corruption

Exim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname into a buffer
CVE-2020-28010 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname into a buffer that is too small (on some common platforms).

Memory Corruption

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads
CVE-2020-28009 7.8 - High - May 06, 2021

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads that are accompanied by unbounded increases in a certain size variable. NOTE: exploitation may be impractical because of the execution time needed to overflow (multiple days).

Integer Overflow or Wraparound

Exim 4 before 4.94.2
CVE-2020-28017 9.8 - Critical - May 06, 2021

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow in receive_add_recipient via an e-mail message with fifty million recipients. NOTE: remote exploitation may be difficult because of resource consumption.

Integer Overflow or Wraparound

Exim through 4.93 has an out-of-bounds read in the SPA authenticator
CVE-2020-12783 - May 11, 2020

Exim through 4.93 has an out-of-bounds read in the SPA authenticator that could result in SPA/NTLM authentication bypass in auths/spa.c and auths/auth-spa.c.