Skip to content
Fencer Vulns
medium 6.5

CVE-2026-43951 json

Apache HTTP Server: OOB Read in `merge_response_headers` can cause crash

published 2026-06-08 5 mo ago modified 2026-09-08 2 mo ago also BIT-apache-2026-43951 , EUVD-2026-35093

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 46%
public exploits
0
none known

Summary

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.

Patch / fix

  • bitnami apache 2.4.68
  • apache http_server 2.4.68
  • apache2 Debian 12 2.4.68-1~deb12u1
  • apache2 Debian 13 2.4.68-1~deb13u1
  • apache2 Debian 14 2.4.68-1

debian advisories DEBIAN-CVE-2026-43951

  • apache2 Ubuntu 22.04 LTS 2.4.52-1ubuntu4.23
  • apache2 Ubuntu 24.04 LTS 2.4.58-1ubuntu8.15
  • apache2 Ubuntu 26.04 LTS 2.4.66-2ubuntu2.4
  • apache2 Ubuntu Pro 14.04 LTS 2.4.7-1ubuntu4.22+esm14
  • apache2 Ubuntu Pro 16.04 LTS 2.4.18-2ubuntu3.17+esm19
  • apache2 Ubuntu Pro 18.04 LTS 2.4.29-1ubuntu4.27+esm10
  • apache2 Ubuntu Pro 20.04 LTS 2.4.41-4ubuntu3.23+esm5

ubuntu advisories UBUNTU-CVE-2026-43951

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jbcs-httpd24-httpd jboss core services 1 2.4.62-16.el8jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.62-16.el8jbcs
  • jbcs-httpd24-mod_ldap jboss core services 1 2.4.62-16.el8jbcs
  • jbcs-httpd24-mod_http2 jboss core services 1 2.0.29-13.el8jbcs
  • jbcs-httpd24-httpd-tools jboss core services 1 2.4.62-16.el8jbcs
  • jbcs-httpd24-mod_session jboss core services 1 2.4.62-16.el8jbcs
  • jbcs-httpd24-httpd-manual jboss core services 1 2.4.62-16.el8jbcs
  • jbcs-httpd24-httpd-selinux jboss core services 1 2.4.62-16.el8jbcs

red hat advisories RHSA-2026:67152RHSA-2026:66323RHSA-2026:62165RHSA-2026:56868RHSA-2026:59387RHSA-2026:55992

  • apache2 SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2-event SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2-utils SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2-manual SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2-worker SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2-prefork SLES for SAP applications 16.0, SLES 16.0 2.4.66-160000.3.1
  • apache2 SLE Module for Basesystem 15 SP7 2.4.66-150700.4.23.1
  • apache2-event SLE Module for Package Hub 15 SP7 2.4.66-150700.4.23.1

suse advisories SUSE-SU-2026:22564-1SUSE-SU-2026:2759-1SUSE-SU-2026:2735-1SUSE-SU-2026:2717-1SUSE-SU-2026:2686-1

  • apache2 openSUSE Leap 16.0 2.4.66-160000.3.1
  • apache2-event openSUSE Leap 16.0 2.4.66-160000.3.1
  • apache2-utils openSUSE Leap 16.0 2.4.66-160000.3.1
  • apache2-manual openSUSE Leap 16.0 2.4.66-160000.3.1
  • apache2-worker openSUSE Leap 16.0 2.4.66-160000.3.1
  • apache2-prefork openSUSE Leap 16.0 2.4.66-160000.3.1

opensuse advisories openSUSE-SU-2026:21235-1

  • mod_http2 AlmaLinux 9 2.0.26-6.el9_8.2
  • httpd AlmaLinux 8 2.4.37-65.module_el8.10.0+4233+8b7d9181.9
  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.10.0+4088+57f011c1.2
  • mod_ssl AlmaLinux 8 1:2.4.37-65.module_el8.10.0+4233+8b7d9181.9
  • mod_ldap AlmaLinux 8 2.4.37-65.module_el8.10.0+4233+8b7d9181.9
  • mod_http2 AlmaLinux 8 1.15.7-10.module_el8.10.0+4233+8b7d9181.7
  • httpd-tools AlmaLinux 8 2.4.37-65.module_el8.10.0+4233+8b7d9181.9
  • mod_session AlmaLinux 8 2.4.37-65.module_el8.10.0+4233+8b7d9181.9

almalinux advisories ALSA-2026:59387ALSA-2026:42828ALSA-2026:41906ALSA-2026:34109ALSA-2026:34355

  • mod_http2 Rocky Linux 9 2.0.26-6.el9_8.2
  • httpd Rocky Linux 9 2.4.62-13.el9_8.5
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1984+1bed3124.4
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1938+3b7755d4.3
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+40045+6ce8579b.6
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+40206+be2c8a50.8
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+40053+5a18018e.7
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1830+22f0c9e0

rocky linux advisories RLSA-2026:59387RLSA-2026:41906RLSA-2026:42828RLSA-2026:34355

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 2.4.68-r0

alpine advisories ALPINE-CVE-2026-43951

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • httpd Azure Linux 3.0 2.4.68-1

azure linux advisories AZL-89729

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-43951 updated cvss 6.5

httpd: Apache HTTP Server: Out-of-bounds Read in mod_headers and mod_mime

  • Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat JBoss Core Services mod_http2.so
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux AppStream (v. 8) mod_md 2.0.8-8.module+el8.10.0+23815+1b5e1c66.2, httpd 2.4.37-65.module+el8.10.0+24521+219dcfc5.9, mod_ssl 2.4.37-65.module+el8.10.0+24521+219dcfc5.9, mod_ldap 2.4.37-65.module+el8.10.0+24521+219dcfc5.9, mod_http2 1.15.7-10.module+el8.10.0+24521+219dcfc5.7, httpd-tools 2.4.37-65.module+el8.10.0+24521+219dcfc5.9, +4 more
    fixed: vendor fix RHSA-2026:42828
  • Red Hat Enterprise Linux AppStream (v. 9) httpd 2.4.62-13.el9_8.5, mod_lua 2.4.62-13.el9_8.5, mod_ssl 2.4.62-13.el9_8.5, mod_http2 2.0.26-6.el9_8.2, mod_ldap 2.4.62-13.el9_8.5, httpd-core 2.4.62-13.el9_8.5, +5 more
    fixed: vendor fix RHSA-2026:41906
  • Red Hat Enterprise Linux AppStream (v. 10) httpd 2.4.63-13.el10_2.4, mod_lua 2.4.63-13.el10_2.4, mod_ssl 2.4.63-13.el10_2.4, mod_http2 2.0.29-4.el10_2.2, mod_ldap 2.4.63-13.el10_2.4, httpd-core 2.4.63-13.el10_2.4, +5 more
    fixed: vendor fix RHSA-2026:34109
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) httpd 2.4.53-11.el9_2.15, mod_http2 1.15.19-4.el9_2.8, httpd-core 2.4.53-11.el9_2.15
    fixed: vendor fix RHSA-2026:67152
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) httpd 2.4.57-11.el9_4.5, mod_http2 2.0.26-2.el9_4.3, httpd-core 2.4.57-11.el9_4.5
    fixed: vendor fix RHSA-2026:66323
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) mod_http2 2.0.29-2.el10_0.2
    fixed: vendor fix RHSA-2026:50538
show 6 more
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) httpd 2.4.62-4.el9_6.6, mod_lua 2.4.62-4.el9_6.6, mod_ssl 2.4.62-4.el9_6.6, mod_ldap 2.4.62-4.el9_6.6, mod_http2 2.0.26-4.el9_6.2, httpd-core 2.4.62-4.el9_6.6, +5 more
    fixed: vendor fix RHSA-2026:62165
  • Red Hat Hardened Images httpd 2.4.68-1.hum1, httpd-core 2.4.68-1.hum1, httpd-tools 2.4.68-1.hum1, httpd-manual 2.4.68-1.hum1, httpd-filesystem 2.4.68-1.hum1
    fixed: vendor fix RHSA-2026:25042
  • Red Hat Insights proxy 1.5 insights-proxy/insights-proxy-container-rhel9 1786433656
    fixed: vendor fix RHSA-2026:53371
  • Red Hat JBoss Core Services 2.4.62.SP5
    fixed: vendor fix RHSA-2026:56869
  • Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.62-16.el8jbcs, jbcs-httpd24-mod_ssl 2.4.62-16.el8jbcs, jbcs-httpd24-mod_ldap 2.4.62-16.el8jbcs, jbcs-httpd24-httpd-tools 2.4.62-16.el8jbcs, jbcs-httpd24-mod_session 2.4.62-16.el8jbcs, jbcs-httpd24-httpd-manual 2.4.62-16.el8jbcs, +2 more
    fixed: vendor fix RHSA-2026:56868
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) httpd 2.4.53-11.el9_2.15, mod_lua 2.4.53-11.el9_2.15, mod_ssl 2.4.53-11.el9_2.15, mod_ldap 2.4.53-11.el9_2.15, httpd-tools 2.4.53-11.el9_2.15, mod_session 2.4.53-11.el9_2.15, +3 more Red Hat Enterprise Linux AppStream E4S (v.9.4) httpd 2.4.57-11.el9_4.5, mod_lua 2.4.57-11.el9_4.5, mod_ssl 2.4.57-11.el9_4.5, mod_ldap 2.4.57-11.el9_4.5, httpd-tools 2.4.57-11.el9_4.5, mod_session 2.4.57-11.el9_4.5, +3 more Red Hat Enterprise Linux AppStream EUS (v. 10.0) mod_http2-debuginfo 2.0.29-2.el10_0.2, mod_http2-debugsource 2.0.29-2.el10_0.2 Red Hat Enterprise Linux AppStream EUS (v.9.6) mod_http2-debuginfo 2.0.26-4.el9_6.2, mod_http2-debugsource 2.0.26-4.el9_6.2 Red Hat Hardened Images mod_lua 2.4.68-1.hum1, mod_ssl 2.4.68-1.hum1, mod_ldap 2.4.68-1.hum1, mod_session 2.4.68-1.hum1, mod_proxy_html 2.4.68-1.hum1 Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-mod_md 2.4.28-19.el8jbcs, jbcs-httpd24-mod_http2 2.0.29-13.el8jbcs, jbcs-httpd24-mod_security 2.9.6-19.el8jbcs, jbcs-httpd24-mod_jk 1.2.50-17.redhat_1.el8jbcs, jbcs-httpd24-mod_proxy_cluster 1.3.22-12.el8jbcs, jbcs-httpd24-mod_jk-ap24 1.2.50-17.redhat_1.el8jbcs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
bitnami apache
>=2.4.0, <2.4.68
2.4.68

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.