Vulnerability · Published Jun 8, 2026 · Assigned by apache
CVE-2026-43951Apache HTTP Server: OOB Read in `merge_response_headers` can cause crash
Medium 6.5
In plain English
A medium-severity out-of-bounds read in Apache HTTP Server from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.5%top 54.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Out-of-bounds Read vulnerability in Apache HTTP Server with mod_headers and mod_mime and multiple response languages. This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | httpd | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | httpd | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | httpd | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | httpd-core | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:9 | httpd-core | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | httpd-devel | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | httpd-devel | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | httpd-devel | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | httpd-filesystem | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:9 | httpd-filesystem | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | httpd-manual | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | httpd-manual | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | httpd-manual | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | httpd-tools | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | httpd-tools | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | httpd-tools | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | mod_http2 | 2.0.29-4.el10_2.2 | ALSA-2026:34355 |
| AlmaLinux:8 | mod_http2 | 1.15.7-10.module_el8.10.0+4233+8b7d9181.7 | ALSA-2026:42828 |
| AlmaLinux:9 | mod_http2 | 2.0.26-6.el9_8.2 | ALSA-2026:59387 |
| AlmaLinux:10 | mod_ldap | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | mod_ldap | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | mod_ldap | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | mod_lua | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:9 | mod_lua | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:8 | mod_md | 1:2.0.8-8.module_el8.10.0+4088+57f011c1.2 | ALSA-2026:42828 |
| AlmaLinux:10 | mod_proxy_html | 1:2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | mod_proxy_html | 1:2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | mod_proxy_html | 1:2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | mod_session | 2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | mod_session | 2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | mod_session | 2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| AlmaLinux:10 | mod_ssl | 1:2.4.63-13.el10_2.4 | ALSA-2026:34109 |
| AlmaLinux:8 | mod_ssl | 1:2.4.37-65.module_el8.10.0+4233+8b7d9181.9 | ALSA-2026:42828 |
| AlmaLinux:9 | mod_ssl | 1:2.4.62-13.el9_8.5 | ALSA-2026:41906 |
| Alpine:v3.21 | apache2 | 2.4.68-r0 | ALPINE-CVE-2026-43951 |
| Alpine:v3.22 | apache2 | 2.4.68-r0 | ALPINE-CVE-2026-43951 |
| Alpine:v3.23 | apache2 | 2.4.68-r0 | ALPINE-CVE-2026-43951 |
| Alpine:v3.24 | apache2 | 2.4.68-r0 | ALPINE-CVE-2026-43951 |
| Debian:12 | apache2 | 2.4.68-1~deb12u1 | DEBIAN-CVE-2026-43951 |
| Debian:13 | apache2 | 2.4.68-1~deb13u1 | DEBIAN-CVE-2026-43951 |
| Debian:14 | apache2 | 2.4.68-1 | DEBIAN-CVE-2026-43951 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+2061+8d03fdec.5 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+1984+1bed3124.4 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+1938+3b7755d4.3 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+40045+6ce8579b.6 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+40206+be2c8a50.8 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+40053+5a18018e.7 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+1830+22f0c9e0 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+1842+4a9649e8.2 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+1840+b070a976.1 | RLSA-2026:42828 |
| Rocky Linux:8 | httpd | 0:2.4.37-65.module+el8.10.0+40197+0231e209.8 | RLSA-2026:42828 |
| Rocky Linux:9 | httpd | 0:2.4.62-13.el9_8.5 | RLSA-2026:41906 |
| Rocky Linux:10 | mod_http2 | 0:2.0.29-4.el10_2.2 | RLSA-2026:34355 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+1883+38ed6c58.1 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+2061+8d03fdec.4 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+40197+0231e209.5 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+1830+22f0c9e0 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+1938+3b7755d4.3 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+1775+6b057638 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-10.module+el8.10.0+40204+716978aa.6 | RLSA-2026:42828 |
| Rocky Linux:9 | mod_http2 | 0:2.0.26-6.el9_8.2 | RLSA-2026:59387 |
| Rocky Linux:8 | mod_md | 1:2.0.8-8.module+el8.10.0+40053+5a18018e.2 | RLSA-2026:42828 |
| Rocky Linux:8 | mod_md | 1:2.0.8-8.module+el8.9.0+1370+89cc8ad5 | RLSA-2026:42828 |
| Ubuntu:22.04:LTS | apache2 | 2.4.52-1ubuntu4.23 | USN-8516-1 |
| Ubuntu:22.04:LTS | apache2 | 2.4.52-1ubuntu4.23 | UBUNTU-CVE-2026-43951 |
| Ubuntu:24.04:LTS | apache2 | 2.4.58-1ubuntu8.15 | UBUNTU-CVE-2026-43951 |
| Ubuntu:24.04:LTS | apache2 | 2.4.58-1ubuntu8.15 | USN-8516-1 |
| Ubuntu:25.10 | apache2 | no fix listed | UBUNTU-CVE-2026-43951 |
| Ubuntu:26.04:LTS | apache2 | 2.4.66-2ubuntu2.4 | UBUNTU-CVE-2026-43951 |
| Ubuntu:26.04:LTS | apache2 | 2.4.66-2ubuntu2.4 | USN-8516-1 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache HTTP Server | 2.4.0 – through 2.4.67 |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N