CVE-2023-38709

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.

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.

Apache HTTP Server is a powerful and flexible HTTP/1.1 compliant web server.

Security Fix(es):

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. (CVE-2023-38709)

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.(CVE-2024-24795)

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.(CVE-2024-27316)

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.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd:2.4: httpd: HTTP response splitting (CVE-2023-38709)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd: HTTP response splitting (CVE-2023-38709)
• httpd: HTTP Response Splitting in multiple modules (CVE-2024-24795)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd: incomplete fix for CVE-2023-38709 (CVE-2024-42516)
• httpd: NULL pointer dereference via specially crafted request (CVE-2026-29169)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via malicious backend servers (CVE-2026-34356)
• httpd: Apache HTTP Server: Buffer Over-read via outbound OCSP requests to attacker-controlled server (CVE-2026-44185)
• httpd: Apache HTTP Server: Denial of Service via crafted regular expressions (CVE-2026-44631)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via untrusted content in mod_xml2enc (CVE-2026-42536)
• httpd: Apache HTTP Server: Buffer overflow in mod_proxy_html allows security bypass (CVE-2026-34355)

Bug Fix(es) and Enhancement(s):

• address Moderate severity issues from httpd 2.4.68 [almalinux-10.2.z] (JIRA:AlmaLinux-184518)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd: incomplete fix for CVE-2023-38709 (CVE-2024-42516)
• Apache HTTP Server: mod_rewrite: Apache HTTP Server: Privilege Escalation via .htaccess file manipulation (CVE-2026-24072)
• httpd: mod_auth_digest: timing attack allows a bypass of digest authentication (CVE-2026-33006)
• httpd: NULL pointer dereference via specially crafted request (CVE-2026-29169)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via malicious backend servers (CVE-2026-34356)
• httpd: Apache HTTP Server: Buffer Over-read via outbound OCSP requests to attacker-controlled server (CVE-2026-44185)
• httpd: Apache HTTP Server: Denial of Service via crafted regular expressions (CVE-2026-44631)
• httpd: Apache HTTP Server: Denial of Service in mod_proxy_ftp via attacker-controlled FTP server (CVE-2026-44186)
• httpd: Apache httpd mod_dav_fs: Denial of Service due to path handling issue (CVE-2026-42535)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via untrusted content in mod_xml2enc (CVE-2026-42536)
• httpd: Apache HTTP Server: Buffer overflow in mod_proxy_html allows security bypass (CVE-2026-34355)
• httpd: Apache HTTP Server: Out-of-bounds Read in mod_headers and mod_mime (CVE-2026-43951)
• httpd: Apache HTTP Server: Local .htaccess authors can read files with httpd user privileges (CVE-2026-44119)

Bug Fix(es) and Enhancement(s):

• address Moderate severity issues from httpd 2.4.68 [almalinux-9.8.z] (JIRA:AlmaLinux-184520)
• mod_proxy_html regression in CVE-2026-34355 fix [almalinux-9.8.z] (JIRA:AlmaLinux-192752)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd: incomplete fix for CVE-2023-38709 (CVE-2024-42516)
• httpd: NULL pointer dereference via specially crafted request (CVE-2026-29169)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via malicious backend servers (CVE-2026-34356)
• httpd: Apache HTTP Server: Buffer Over-read via outbound OCSP requests to attacker-controlled server (CVE-2026-44185)
• httpd: Apache HTTP Server: Denial of Service via crafted regular expressions (CVE-2026-44631)
• httpd: Apache HTTP Server: Denial of Service in mod_proxy_ftp via attacker-controlled FTP server (CVE-2026-44186)
• httpd: Apache HTTP Server: Heap-based Buffer Overflow via untrusted content in mod_xml2enc (CVE-2026-42536)
• httpd: Apache HTTP Server: Buffer overflow in mod_proxy_html allows security bypass (CVE-2026-34355)
• httpd: Apache HTTP Server: Out-of-bounds Read in mod_headers and mod_mime (CVE-2026-43951)

Bug Fix(es) and Enhancement(s):

• mod_proxy_html regression in CVE-2026-34355 fix [almalinux-8.10.z] (JIRA:AlmaLinux-192751)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

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.

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.

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.

• CVE-2024-38474: mod_rewrite: server weakness with encoded question marks in backreferences
• CVE-2024-38475: mod_rewrite: server weakness in mod_rewrite when first segment of substitution matches filesystem path
• CVE-2024-38477: mod_proxy: crash resulting in Denial of Service in mod_proxy via a malicious request
• CVE-2023-38709: http_filters: HTTP response splitting
• CVE-2024-38473: mod_proxy: server proxy encoding problem
• CVE-2024-39573: mod_rewrite: proxy handler substitution
• CVE-2024-38476: http: server use exploitable/malicious backend application output to run local handlers via internal redirect
• CVE-2024-39884: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-38476 fix
• CVE-2024-40725: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-39884 fix

• CVE-2024-38474: mod_rewrite: server weakness with encoded question marks in backreferences
• CVE-2024-38475: mod_rewrite: server weakness in mod_rewrite when first segment of substitution matches filesystem path
• CVE-2024-38477: mod_proxy: crash resulting in Denial of Service in mod_proxy via a malicious request
• CVE-2023-38709: http_filters: HTTP response splitting
• CVE-2024-38473: mod_proxy: server proxy encoding problem
• CVE-2024-39573: mod_rewrite: proxy handler substitution
• CVE-2024-38476: http: server use exploitable/malicious backend application output to run local handlers via internal redirect
• CVE-2024-39884: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-38476 fix
• CVE-2024-40725: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-39884 fix

• CVE-2024-38474: mod_rewrite: server weakness with encoded question marks in backreferences
• CVE-2024-38475: mod_rewrite: server weakness in mod_rewrite when first segment of substitution matches filesystem path
• CVE-2024-38477: mod_proxy: crash resulting in Denial of Service in mod_proxy via a malicious request
• CVE-2023-38709: http_filters: HTTP response splitting
• CVE-2024-38473: mod_proxy: server proxy encoding problem
• CVE-2024-39573: mod_rewrite: proxy handler substitution
• CVE-2024-38476: http: server use exploitable/malicious backend application output to run local handlers via internal redirect
• CVE-2024-39884: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-38476 fix
• CVE-2024-40725: modules: source code disclosure with handlers configured via AddType. Resolving regression introduced by CVE-2024-39884 fix

• CVE-2023-38709: faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses
• CVE-2024-24795: HTTP response splitting in multiple modules allows an attacker that can inject malicious response headers into backend applications to cause an HTTP desynchronization attack

• SECURITY UPDATE: Memory exhaustion due to excessive HTTP/2 incoming headers buffering
  • debian/patches/CVE-2024-27316.patch: Fix to bail after too many failed reads, increment count on request headers failed to add
  • CVE-2024-27316
• SECURITY UPDATE: Faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses
  • debian/patches/CVE-2023-38709.patch: header validation after content-* are eval'ed
  • CVE-2023-38709
• SECURITY UPDATE: 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
  • debian/patches/CVE-2024-24795.patch: let httpd handle CL/TE for non-http handlers
  • CVE-2024-24795

• CVE-2023-38709: faulty input validation in the core of Apache allows malicious or exploitable backend/content generators to split HTTP responses
• CVE-2024-24795: HTTP response splitting in multiple modules allows an attacker that can inject malicious response headers into backend applications to cause an HTTP desynchronization attack

Apache has been updated to version 2.4.59 to fix CVE-2024-27316, CVE-2024-24795 and CVE-2023-38709. CVE-2024-27316: Apache HTTP Server: HTTP/2 DoS by memory exhaustion on endless continuation frames (cve.mitre.org) 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. Credits: Bartek Nowotarski (https://nowotarski.info/) CVE-2024-24795: Apache HTTP Server: HTTP Response Splitting in multiple modules (cve.mitre.org) 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. Credits: Keran Mu, Tsinghua University and Zhongguancun Laboratory. CVE-2023-38709: Apache HTTP Server: HTTP response splitting (cve.mitre.org) 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. Credits: Orange Tsai (@orange_8361) from DEVCORE

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd:2.4: httpd: HTTP response splitting (CVE-2023-38709)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The httpd packages provide the Apache HTTP Server, a powerful, efficient, and extensible web server.

Security Fix(es):

• httpd: HTTP response splitting (CVE-2023-38709)

• httpd: HTTP Response Splitting in multiple modules (CVE-2024-24795)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 9.5 Release Notes linked from the References section.

This update for apache2 fixes the following issues:

• CVE-2023-38709: Fixed faulty input validation inside the HTTP response splitting code (bsc#1222330).
• CVE-2024-24795: Fixed handling of malicious HTTP splitting response headers in multiple modules (bsc#1222332).
• CVE-2024-27316: Fixed HTTP/2 CONTINUATION frames that could have been utilized for DoS attacks (bsc#1221401).

This update for apache2 fixes the following issues:

• CVE-2023-38709: Fixed faulty input validation inside the HTTP response splitting code (bsc#1222330).
• CVE-2024-24795: Fixed handling of malicious HTTP splitting response headers in multiple modules (bsc#1222332).
• CVE-2024-27316: Fixed HTTP/2 CONTINUATION frames that could have been utilized for DoS attacks (bsc#1221401).

This update for apache2 fixes the following issues:

• CVE-2023-38709: Fixed faulty input validation inside the HTTP response splitting code (bsc#1222330).
• CVE-2024-24795: Fixed handling of malicious HTTP splitting response headers in multiple modules (bsc#1222332).
• CVE-2024-27316: Fixed HTTP/2 CONTINUATION frames that could have been utilized for DoS attacks (bsc#1221401).

This update for apache2 fixes the following issues:

• CVE-2023-38709: Fixed HTTP response splitting (bsc#1222330).
• CVE-2024-24795: Fixed HTTP response splitting in multiple modules (bsc#1222332).
• CVE-2024-27316: Fixed HTTP/2 CONTINUATION frames can be utilized for DoS attacks (bsc#1221401).

This update for apache2 fixes the following issues

• CVE-2026-23918: http2: double free and possible RCE on early reset (bsc#1263957).
• CVE-2026-24072: mod_rewrite elevation of privileges via ap_expr (bsc#1263935).
• CVE-2026-28780: heap buffer overflow in mod_proxy_ajp via ajp_msg_check_header() (bsc#1264163).
• CVE-2026-29167: mod_ldap per-dir use-after-free (bsc#1267976).
• CVE-2026-29168: allocation of resources without limits in mod_md via OCSP response (bsc#1264150).
• CVE-2026-29169: NULL pointer dereference in mod_dav_lock allows server crash via malicious requests (bsc#1263956).
• CVE-2026-29170: mod_proxy_ftp XSS (bsc#1267977).
• CVE-2026-33006: mod_auth_digest timing attack allows bypass of Digest authentication (bsc#1263955).
• CVE-2026-33007: NULL pointer dereference in mod_authn_socache allows unauthenticated remote user to crash a child processes (bsc#1263954).
• CVE-2026-33523: HTTP response splitting forwarding malicious status line (bsc#1263953).
• CVE-2026-33857: off-by-one OOB reads in AJP getter functions (bsc#1263952).
• CVE-2026-34032: heap buffer overread in mod_proxy_ajp due to missing null-termination check (bsc#1263951).
• CVE-2026-34059: heap buffer overread and memory disclosure via ajp_parse_data() (bsc#1263950).
• CVE-2026-34355: mod_proxy_html buffer overflow (bsc#1267978).
• CVE-2026-34356: malicious backend servers can lead to a heap-based buffer overflow (bsc#1267955).
• CVE-2026-42535: malicious path manipulation can lead to child process crashes (bsc#1267956).
• CVE-2026-42536: processing untrusted content can lead to a heap-based buffer overflow (bsc#1267962).
• CVE-2026-43951: out-of-bound read in merge_response_headers can cause crash (bsc#1267963).
• CVE-2026-44119: improper privilege management can lead to an unauthorized read (bsc#1267965).
• CVE-2026-44185: Stack Buffer Over-Read in mod_ssl OCSP send_request (bsc#1267969).
• CVE-2026-44186: responses from an attacker-controlled FTP backend can lead to resource exhaustion and a denial of service (bsc#1267970).
• CVE-2026-44631: crafted regular expression can lead to a buffer underwrite (bsc#1267971).
• CVE-2026-48913: file handle exhaustion during request processing in mod_http2 can lead to a use-after-free (bsc#1267972).
• CVE-2026-49975: Fix cookie header accounting against LimitRequestFields (bsc#1267503).

Non security issue:

• Update to 2.4.66 (jsc#PED-16334).

Orange Tsai discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2023-38709)

Keran Mu and Jianjun Chen discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2024-24795)

Bartek Nowotarski discovered that the Apache HTTP Server HTTP/2 module incorrectly handled endless continuation frames. A remote attacker could possibly use this issue to cause the server to consume resources, leading to a denial of service. (CVE-2024-27316)

USN-6729-1 fixed several vulnerabilities in Apache. This update provides the corresponding update for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

Orange Tsai discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2023-38709)

Keran Mu and Jianjun Chen discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2024-24795)

Bartek Nowotarski discovered that the Apache HTTP Server HTTP/2 module incorrectly handled endless continuation frames. A remote attacker could possibly use this issue to cause the server to consume resources, leading to a denial of service. This issue was addressed only in Ubuntu 18.04 LTS. (CVE-2024-27316)

USN-6729-1 fixed vulnerabilities in Apache HTTP Server. This update provides the corresponding updates for Ubuntu 24.04 LTS.

Original advisory details:

Orange Tsai discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2023-38709)

Keran Mu and Jianjun Chen discovered that the Apache HTTP Server incorrectly handled validating certain input. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2024-24795)

Bartek Nowotarski discovered that the Apache HTTP Server HTTP/2 module incorrectly handled endless continuation frames. A remote attacker could possibly use this issue to cause the server to consume resources, leading to a denial of service. (CVE-2024-27316)

It was discovered that Apache HTTP Server incorrectly handled certain response headers. An attacker could possibly use this issue to perform HTTP response splitting attacks. This issue only affected Ubuntu 14.04 LTS. (CVE-2023-38709)

Will Dormann and David Warren discovered that Apache HTTP Server's HTTP/2 implementation did not properly reclaim memory when streams were reset by clients. A remote attacker could possibly use this issue to cause Apache HTTP Server to consume resources, leading to a denial of service. This issue only affected Ubuntu 18.04 LTS. (CVE-2023-45802)

Keran Mu and Jianjun Chen discovered that Apache HTTP Server incorrectly handled certain response headers. An attacker could possibly use this issue to perform HTTP response splitting attacks. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-24795)

Orange Tsai discovered that Apache HTTP Server mod_proxy incorrectly handled URL encoding. A remote attacker could possibly use this issue to bypass authentication via crafted requests. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. (CVE-2024-38473)

Orange Tsai discovered that Apache HTTP Server could be caused to perform server-side request forgery (SSRF) via malicious backend response headers. A remote attacker could possibly use this issue to conduct SSRF attacks or disclose sensitive information. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-38476)

Orange Tsai discovered that Apache HTTP Server mod_proxy did not properly handle certain null pointer conditions. A remote attacker could possibly use this issue to cause Apache HTTP Server to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-38477)

Orange Tsai discovered that Apache HTTP Server mod_rewrite could be made to perform server-side request forgery (SSRF) via unsafe RewriteRules. A remote attacker could possibly use this issue to conduct SSRF attacks. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. (CVE-2024-39573)

It was discovered that Apache HTTP Server incorrectly handled certain response headers. An attacker could possibly use this issue to perform HTTP response splitting attacks. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-42516)

It was discovered that Apache HTTP Server could be caused to perform server-side request forgery (SSRF) via mod_headers modifying Content-Type headers. A remote attacker could possibly use this issue to conduct SSRF attacks. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-43204)

John Runyon discovered that Apache HTTP Server mod_ssl did not properly escape user-supplied data before writing log entries. A remote attacker could possibly use this issue to insert escape sequences into log files. This issue only affected Ubuntu 14.04 LTS. (CVE-2024-47252)

Robert Merget discovered that Apache HTTP Server with SSLEngine optional was vulnerable to HTTP desynchronisation attacks. An attacker in a privileged network position could possibly use this issue to hijack HTTP sessions. This issue only affected Ubuntu 14.04 LTS. (CVE-2025-49812)

It was discovered that Apache HTTP Server mod_md had an integer overflow in the ACME certificate renewal backoff timer. An attacker could possibly use this issue to cause excessive certificate renewal requests. This issue only affected Ubuntu 20.04 LTS. (CVE-2025-55753)

Anthony Parfenov discovered that Apache HTTP Server with SSI enabled and mod_cgid passed shell-escaped query strings to #exec cmd directives. A remote attacker could possibly use this issue to perform command injection. (CVE-2025-58098)

Mattias Åsander discovered that Apache HTTP Server incorrectly gave precedence to environment variables from HTTP headers over server-calculated CGI variables. A remote attacker could possibly use this issue to influence the environment of CGI programs. (CVE-2025-65082)

Mattias Åsander discovered that Apache HTTP Server mod_userdir with suexec could be caused to run CGI scripts under…