Apache HTTP Server

Apache HTTP Server 2.4.66 mod_proxy_ajp Heap Buffer Overflow (CVE-2026-28780)
CVE-2026-28780 9.8 - Critical - May 05, 2026

Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Heap-based Buffer Overflow

Apache HTTP Server 2.4.30-2.4.66 mod_md OCSP Resource Exhaustion Vulnerability
CVE-2026-29168 7.3 - High - May 05, 2026

Allocation of Resources Without Limits or Throttling vulnerability in Apache HTTP Server's  mod_md via OCSP response data. This issue affects Apache HTTP Server: from 2.4.30 through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Allocation of Resources Without Limits or Throttling

Apache HTTP Server 2.4.66 mod_dav_lock Null PTR Crash
CVE-2026-29169 7.5 - High - May 04, 2026

A NULL pointer dereference in mod_dav_lock in Apache HTTP Server 2.4.66 and earlier may allow an attacker to crash the server with a malicious request.mod_dav_lock is not used internally by mod_dav or mod_dav_fs. The only known use-case for mod_dav_lock was mod_dav_svn from Apache Subversion earlier than version 1.2.0. Users are recommended to upgrade to version 2.4.66, which fixes this issue, or remove mod_dav_lock.

NULL Pointer Dereference

Apache HTTP Server 2.4.66 Double Free via HTTP/2 (possible RCE)
CVE-2026-23918 8.8 - High - May 04, 2026

Double Free and possible RCE vulnerability in Apache HTTP Server with the HTTP/2 protocol. This issue affects Apache HTTP Server: 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Double-free

Timing Att. Mod Auth Digest Bypass in Apache HTTP Server 2.4.66
CVE-2026-33006 4.8 - Medium - May 04, 2026

A timing attack against mod_auth_digest in Apache HTTP Server 2.4.66 allows a bypass of Digest authentication by a remote attacker. Users are recommended to upgrade to version 2.4.67, which fixes this issue.

Observable Timing Discrepancy

Apache HTTP Server 2.4.66: mod_authn_socache NULL deref crash (before 2.4.67)
CVE-2026-33007 5.3 - Medium - May 04, 2026

A NULL pointer dereference in the mod_authn_socache in Apache HTTP Server 2.4.66 and earlier allows an unauthenticated remote user to crash a child process in a caching forward proxy configuration. Users are recommended to upgrade to version 2.4.67, which fixes this issue.

NULL Pointer Dereference

Apache HTTP Server 2.4.66 Response Splitting via Modules
CVE-2026-33523 6.5 - Medium - May 04, 2026

HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend servers. This issue affects Apache HTTP Server: from through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

DEPRECATED (Duplicate): HTTP response splitting

Apache HTTP Server 2.4.66: OOB Read in mod_proxy_ajp (fixed 2.4.67)
CVE-2026-33857 5.3 - Medium - May 04, 2026

Out-of-bounds Read vulnerability in mod_proxy_ajp of Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Out-of-bounds Read

Apache HTTP Server <=2.4.66 Null-Termination OOB Read
CVE-2026-34032 5.3 - Medium - May 04, 2026

Improper Null Termination, Out-of-bounds Read vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Improper Null Termination

Apache HTTP Server 2.4.66 Buffer Over-Read Vulnerability
CVE-2026-34059 7.5 - High - May 04, 2026

Buffer Over-read vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Buffer Over-read

CVE-2026-24072: Apache HTTPD 2.4.66-2.4.67 Priv Escalation via .htaccess
CVE-2026-24072 8.8 - High - May 04, 2026

An escalation of privilege bug in various modules in Apache HTTP 2.4.66 and earlier allows local .htaccess authors to read files with the privileges of the httpd user. Users are recommended to upgrade to version 2.4.67, which fixes this issue.

Improper Privilege Management

Apache HTTP Server <2.4.66: SSI Exec Cmd Shell Injection via mod_cgid
CVE-2025-58098 8.3 - High - December 05, 2025

Apache HTTP Server 2.4.65 and earlier with Server Side Includes (SSI) enabled and mod_cgid (but not mod_cgi) passes the shell-escaped query string to #exec cmd="..." directives. This issue affects Apache HTTP Server before 2.4.66. Users are recommended to upgrade to version 2.4.66, which fixes the issue.

Insertion of Sensitive Information Into Sent Data

Apache HTTP Server 2.4.765 AllowOverride FileInfo Bypass
CVE-2025-66200 5.4 - Medium - December 05, 2025

mod_userdir+suexec bypass via AllowOverride FileInfo vulnerability in Apache HTTP Server. Users with access to use the RequestHeader directive in htaccess can cause some CGI scripts to run under an unexpected userid. This issue affects Apache HTTP Server: from 2.4.7 through 2.4.65. Users are recommended to upgrade to version 2.4.66, which fixes the issue.

Authentication Bypass Using an Alternate Path or Channel

Apache HTTP Server 2.4.02.4.65 ENV Var XSS via config, fixed in 2.4.66
CVE-2025-65082 6.5 - Medium - December 05, 2025

Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in Apache HTTP Server through environment variables set via the Apache configuration unexpectedly superseding variables calculated by the server for CGI programs. This issue affects Apache HTTP Server from 2.4.0 through 2.4.65. Users are recommended to upgrade to version 2.4.66 which fixes the issue.

Improper Neutralization of Escape, Meta, or Control Sequences

Apache HTTP Server SSRF NTLM Leak via AllowEncodedSlashes, Fixed 2.4.66
CVE-2025-59775 7.5 - High - December 05, 2025

Server-Side Request Forgery (SSRF) vulnerability  in Apache HTTP Server on Windows with AllowEncodedSlashes On and MergeSlashes Off  allows to potentially leak NTLM hashes to a malicious server via SSRF and malicious requests or content Users are recommended to upgrade to version 2.4.66, which fixes the issue.

SSRF

Apache HTTPd 2.4.30-2.4.65 Integer Overflow in ACME Renewal Zero Backoff Timer
CVE-2025-55753 7.5 - High - December 05, 2025

An integer overflow in the case of failed ACME certificate renewal leads, after a number of failures (~30 days in default configurations), to the backoff timer becoming 0. Attempts to renew the certificate then are repeated without delays until it succeeds. This issue affects Apache HTTP Server: from 2.4.30 before 2.4.66. Users are recommended to upgrade to version 2.4.66, which fixes the issue.

Integer Overflow or Wraparound

Apache HTTP Server DoS via crafted HTTP requests
CVE-2025-64388 - October 31, 2025

Denial of service of the web server through specific requests to this protocol

Resource Exhaustion

Apache HTTP 2.4.64: RewriteCond expr always true bug
CVE-2025-54090 6.3 - Medium - July 23, 2025

A bug in Apache HTTP Server 2.4.64 results in all "RewriteCond expr ..." tests evaluating as "true". Users are recommended to upgrade to version 2.4.65, which fixes the issue.

Incorrect Check of Function Return Value

Apache HTTP Server Memory Leak before 2.4.64 (CVE-2025-53020)
CVE-2025-53020 7.5 - High - July 10, 2025

Late Release of Memory after Effective Lifetime vulnerability in Apache HTTP Server. This issue affects Apache HTTP Server: from 2.4.17 up to 2.4.63. Users are recommended to upgrade to version 2.4.64, which fixes the issue.

Memory Leak

Apache HTTP Server 2.4.63 & earlier mod_ssl: HTTP Desync via TLS Upgrade
CVE-2025-49812 7.4 - High - July 10, 2025

In some mod_ssl configurations on Apache HTTP Server versions through to 2.4.63, an HTTP desynchronisation attack allows a man-in-the-middle attacker to hijack an HTTP session via a TLS upgrade. Only configurations using "SSLEngine optional" to enable TLS upgrades are affected. Users are recommended to upgrade to version 2.4.64, which removes support for TLS upgrade.

authentification

Apache HTTP Server 2.4.x: mod_proxy_http2 assertion triggers DoS via proxy
CVE-2025-49630 7.5 - High - July 10, 2025

In certain proxy configurations, a denial of service attack against Apache HTTP Server versions 2.4.26 through to 2.4.63 can be triggered by untrusted clients causing an assertion in mod_proxy_http2. Configurations affected are a reverse proxy is configured for an HTTP/2 backend, with ProxyPreserveHost set to "on".

assertion failure

Apache Httpd 2.4.35-2.4.63 mod_ssl TLS1.3 SR Access Ctrl Bypass
CVE-2025-23048 9.1 - Critical - July 10, 2025

In some mod_ssl configurations on Apache HTTP Server 2.4.35 through to 2.4.63, an access control bypass by trusted clients is possible using TLS 1.3 session resumption. Configurations are affected when mod_ssl is configured for multiple virtual hosts, with each restricted to a different set of trusted client certificates (for example with a different SSLCACertificateFile/Path setting). In such a case, a client trusted to access one virtual host may be able to access another virtual host, if SSLStrictSNIVHostCheck is not enabled in either virtual host.

Authorization

Apache HTTP Server 2.4.63 mod_ssl log injection via unsanitized SSL var
CVE-2024-47252 7.5 - High - July 10, 2025

Insufficient escaping of user-supplied data in mod_ssl in Apache HTTP Server 2.4.63 and earlier allows an untrusted SSL/TLS client to insert escape characters into log files in some configurations. In a logging configuration where CustomLog is used with "%{varname}x" or "%{varname}c" to log variables provided by mod_ssl such as SSL_TLS_SNI, no escaping is performed by either mod_log_config or mod_ssl and unsanitized data provided by the client may appear in log files.

Improper Neutralization of Escape, Meta, or Control Sequences

Apache HTTP Server SSRF via mod_rewrite/expressions (2.4.0-2.4.63)
CVE-2024-43394 7.5 - High - July 10, 2025

Server-Side Request Forgery (SSRF) in Apache HTTP Server on Windows allows to potentially leak NTLM hashes to a malicious server via  mod_rewrite or apache expressions that pass unvalidated request input. This issue affects Apache HTTP Server: from 2.4.0 through 2.4.63. Note:  The Apache HTTP Server Project will be setting a higher bar for accepting vulnerability reports regarding SSRF via UNC paths. The server offers limited protection against administrators directing the server to open UNC paths. Windows servers should limit the hosts they will connect over via SMB based on the nature of NTLM authentication.

SSRF

Apache HTTP Server 2.4.x SSRF via mod_proxy+mod_headers (before 2.4.64)
CVE-2024-43204 7.5 - High - July 10, 2025

SSRF in Apache HTTP Server with mod_proxy loaded allows an attacker to send outbound proxy requests to a URL controlled by the attacker.  Requires an unlikely configuration where mod_headers is configured to modify the Content-Type request or response header with a value provided in the HTTP request. Users are recommended to upgrade to version 2.4.64 which fixes this issue.

SSRF

Apache HTTP Server 2.4.64+ fixes HTTP response splitting in core
CVE-2024-42516 7.5 - High - July 10, 2025

HTTP response splitting in the core of Apache HTTP Server allows an attacker who can manipulate the Content-Type response headers of applications hosted or proxied by the server can split the HTTP response. This vulnerability was described as CVE-2023-38709 but the patch included in Apache HTTP Server 2.4.59 did not address the issue. Users are recommended to upgrade to version 2.4.64, which fixes this issue.

Improper Input Validation

Apache HTTPD Insecure Config: Directory Listing via Unnecessary Modules
CVE-2025-27452 - July 03, 2025

The configuration of the Apache httpd webserver which serves the MEAC300-FNADE4 web application, is partly insecure. There are modules activated that are not required for the operation of the FNADE4 web application. The functionality of the some modules pose a risk to the webserver which enable dircetory listing.

Apache mod_auth_openidc POST Crash via OIDCPreservePost
CVE-2025-3891 7.5 - High - April 29, 2025

A flaw was found in the mod_auth_openidc module for Apache httpd. This flaw allows a remote, unauthenticated attacker to trigger a denial of service by sending an empty POST request when the OIDCPreservePost directive is enabled. The server crashes consistently, affecting availability.

Uncaught Exception

Apache HTTP Server mod_proxy_cluster <Directory> misconfig allows MCMP hijack
CVE-2024-10306 5.4 - Medium - April 23, 2025

A vulnerability was found in mod_proxy_cluster. The issue is that the <Directory> directive should be replaced by the <Location> directive as the former does not restrict IP/host access as `Require ip IP_ADDRESS` would suggest. This means that anyone with access to the host might send MCMP requests that may result in adding/removing/updating nodes for the balancing. However, this host should not be accessible to the public network as it does not serve the general traffic.

AuthZ

D-Link DAP-2310 ATP Binary Buffer Overflow 1.16RC028
CVE-2024-45623 - September 02, 2024

D-Link DAP-2310 Hardware A Firmware 1.16RC028 allows remote attackers to execute arbitrary code via a stack-based buffer overflow in the ATP binary that handles PHP HTTP GET requests for the Apache HTTP Server (httpd). NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

SSRF via mod_rewrite in Apache HTTP Server on Windows (pre-2.4.62)
CVE-2024-40898 7.5 - High - July 18, 2024

SSRF in Apache HTTP Server on Windows with mod_rewrite in server/vhost context, allows to potentially leak NTML hashes to a malicious server via SSRF and malicious requests. Users are recommended to upgrade to version 2.4.62 which fixes this issue. 

SSRF

Apache HTTPD 2.4.61 Local Disclosure via Legacy ContentType Config
CVE-2024-40725 5.3 - Medium - July 18, 2024

A partial fix for  CVE-2024-39884 in the core of Apache HTTP Server 2.4.61 ignores some use of the legacy content-type based configuration of handlers. "AddType" and similar configuration, under some circumstances where files are requested indirectly, result in source code disclosure of local content. For example, PHP scripts may be served instead of interpreted. Users are recommended to upgrade to version 2.4.62, which fixes this issue.

Exposure of Resource to Wrong Sphere

Apache HTTP Server 2.4.60 regression enables local source disclosure via AddType
CVE-2024-39884 - July 04, 2024

A regression in the core of Apache HTTP Server 2.4.60 ignores some use of the legacy content-type based configuration of handlers.   "AddType" and similar configuration, under some circumstances where files are requested indirectly, result in source code disclosure of local content. For example, PHP scripts may be served instead of interpreted. Users are recommended to upgrade to version 2.4.61, which fixes this issue.

Apache HTTP Server mod_rewrite SSRF before 2.4.60 via mod_proxy
CVE-2024-39573 7.5 - High - July 01, 2024

Potential SSRF in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to cause unsafe RewriteRules to unexpectedly setup URL's to be handled by mod_proxy. Users are recommended to upgrade to version 2.4.60, which fixes this issue.

Improper Input Validation

Null Pointer deref on WebSocket over HTTP/2 upgrade in Jetty
CVE-2024-36387 - July 01, 2024

Serving WebSocket protocol upgrades over a HTTP/2 connection could result in a Null Pointer dereference, leading to a crash of the server process, degrading performance.

NULL Pointer Dereference

Apache HTTP Server <2.4.60 SSRF on Windows leaks NTLM Hashes
CVE-2024-38472 - July 01, 2024

SSRF in Apache HTTP Server on Windows allows to potentially leak NTLM hashes to a malicious server via SSRF and malicious requests or content Users are recommended to upgrade to version 2.4.60 which fixes this issue.  Note: Existing configurations that access UNC paths will have to configure new directive "UNCList" to allow access during request processing.

Apache 2.4.59 mod_proxy URL Encoding Flaw Auth Bypass
CVE-2024-38473 - July 01, 2024

Encoding problem in mod_proxy in Apache HTTP Server 2.4.59 and earlier allows request URLs with incorrect encoding to be sent to backend services, potentially bypassing authentication via crafted requests. Users are recommended to upgrade to version 2.4.60, which fixes this issue.

Output Sanitization

Apache HTTP Server 2.4.59 mod_rewrite RCE (CVE-2024-38474)
CVE-2024-38474 9.8 - Critical - July 01, 2024

Substitution encoding issue in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows attacker to execute scripts in directories permitted by the configuration but not directly reachable by any URL or source disclosure of scripts meant to only to be executed as CGI. Users are recommended to upgrade to version 2.4.60, which fixes this issue. Some RewriteRules that capture and substitute unsafely will now fail unless rewrite flag "UnsafeAllow3F" is specified.

Output Sanitization

Apache HTTP Server 2.4.59 and earlier: mod_rewrite Improper Escaping Bypass
CVE-2024-38475 9.1 - Critical - July 01, 2024

Improper escaping of output in mod_rewrite in Apache HTTP Server 2.4.59 and earlier allows an attacker to map URLs to filesystem locations that are permitted to be served by the server but are not intentionally/directly reachable by any URL, resulting in code execution or source code disclosure. Substitutions in server context that use a backreferences or variables as the first segment of the substitution are affected.  Some unsafe RewiteRules will be broken by this change and the rewrite flag "UnsafePrefixStat" can be used to opt back in once ensuring the substitution is appropriately constrained.

Output Sanitization

Apache HTTP Server 2.4.59 Info Disclosure/SSRF via Malicious Response Headers
CVE-2024-38476 9.8 - Critical - July 01, 2024

Vulnerability in core of Apache HTTP Server 2.4.59 and earlier are vulnerably to information disclosure, SSRF or local script execution via backend applications whose response headers are malicious or exploitable. Users are recommended to upgrade to version 2.4.60, which fixes this issue.

Inclusion of Functionality from Untrusted Control Sphere

Apache HTTP Server 2.4.59 NPE in mod_proxy Crash (Upgrade to 2.4.60)
CVE-2024-38477 7.5 - High - July 01, 2024

null pointer dereference in mod_proxy in Apache HTTP Server 2.4.59 and earlier allows an attacker to crash the server via a malicious request. Users are recommended to upgrade to version 2.4.60, which fixes this issue.

NULL Pointer Dereference

Apache HTTP Server Response Splitting via Faulty Input Validation < 2.4.58
CVE-2023-38709 7.3 - High - April 04, 2024

Faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses. This issue affects Apache HTTP Server: through 2.4.58.

Improper Validation of Specified Quantity in Input

nghttp2 Memory Exhaustion via HTTP/2 Header Buffer Overflow
CVE-2024-27316 7.5 - High - April 04, 2024

HTTP/2 incoming headers exceeding the limit are temporarily buffered in nghttp2 in order to generate an informative HTTP 413 response. If a client does not stop sending headers, this leads to memory exhaustion.

Allocation of Resources Without Limits or Throttling

Apache HTTP Server 2.4.59 Resolved HTTP Response Splitting in Modules
CVE-2024-24795 - April 04, 2024

HTTP Response splitting in multiple modules in Apache HTTP Server allows an attacker that can inject malicious response headers into backend applications to cause an HTTP desynchronization attack. Users are recommended to upgrade to version 2.4.59, which fixes this issue.

Elementor Pro WP Pro v<=3.20.1 Stored XSS via SVGZ Upload on NGINX
CVE-2024-1521 6.4 - Medium - March 27, 2024

The Elementor Website Builder Pro plugin for WordPress is vulnerable to Stored Cross-Site Scripting via an SVGZ file uploaded via the Form widget in all versions up to, and including, 3.20.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. NOTE: This vulnerability is only exploitable on web servers running NGINX. It is not exploitable on web servers running Apache HTTP Server.

XSS

Apache bRPC v0.9.5-1.7.0 HTTP Request Smuggling before 1.8.0
CVE-2024-23452 7.5 - High - February 08, 2024

Request smuggling vulnerability in HTTP server in Apache bRPC 0.9.5~1.7.0 on all platforms allows attacker to smuggle request. Vulnerability Cause Description: The http_parser does not comply with the RFC-7230 HTTP 1.1 specification. Attack scenario: If a message is received with both a Transfer-Encoding and a Content-Length header field, such a message might indicate an attempt to perform request smuggling or response splitting. One particular attack scenario is that a bRPC made http server on the backend receiving requests in one persistent connection from frontend server that uses TE to parse request with the logic that 'chunk' is contained in the TE field. in that case an attacker can smuggle a request into the connection to the backend server.  Solution: You can choose one solution from below: 1. Upgrade bRPC to version 1.8.0, which fixes this issue. Download link: https://github.com/apache/brpc/releases/tag/1.8.0 2. Apply this patch:  https://github.com/apache/brpc/pull/2518

HTTP Request Smuggling

Apache HTTP Server HTTP/2 Window Size 0 Denial of Service (v2.4.5557)
CVE-2023-43622 7.5 - High - October 23, 2023

An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known "slow loris" attack pattern. This has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout. This issue affects Apache HTTP Server: from 2.4.55 through 2.4.57. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

Resource Exhaustion

Apache Httpd 2.4.58 Memory Leak on HTTP/2 RST Stream
CVE-2023-45802 5.9 - Medium - October 23, 2023

When a HTTP/2 stream was reset (RST frame) by a client, there was a time window were the request's memory resources were not reclaimed immediately. Instead, de-allocation was deferred to connection close. A client could send new requests and resets, keeping the connection busy and open and causing the memory footprint to keep on growing. On connection close, all resources were reclaimed, but the process might run out of memory before that. This was found by the reporter during testing of CVE-2023-44487 (HTTP/2 Rapid Reset Exploit) with their own test client. During "normal" HTTP/2 use, the probability to hit this bug is very low. The kept memory would not become noticeable before the connection closes or times out. Users are recommended to upgrade to version 2.4.58, which fixes the issue.

Improper Resource Shutdown or Release

Apache HTTP Server 2.4.57 OutofBounds Read in mod_macro
CVE-2023-31122 7.5 - High - October 23, 2023

Out-of-bounds Read vulnerability in mod_macro of Apache HTTP Server.This issue affects Apache HTTP Server: through 2.4.57.

Out-of-bounds Read

HTTP/2 DoS via Stream Reset in nginx
CVE-2023-44487 7.5 - High - October 10, 2023

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

Resource Exhaustion