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Fencer Vulns
medium 6.5

CVE-2026-33523 json

Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line

published 2026-05-04 6 mo ago modified 2026-10-26 13 d ago also BIT-apache-2026-33523 , EUVD-2026-26965

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

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.

Patch / fix

  • bitnami apache 2.4.67
  • apache http_server 2.4.67
  • apache2 Debian 12 2.4.67-1~deb12u2
  • apache2 Debian 13 2.4.67-1~deb13u2
  • apache2 Debian 14 2.4.67-1

debian advisories DEBIAN-CVE-2026-33523

  • apache2 Ubuntu 22.04 LTS 2.4.52-1ubuntu4.20
  • apache2 Ubuntu 24.04 LTS 2.4.58-1ubuntu8.12
  • apache2 Ubuntu 25.10 2.4.64-1ubuntu3.4
  • apache2 Ubuntu 26.04 LTS 2.4.66-2ubuntu2.1
  • 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-2026-33523

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 2.4.62-17.el8jbcs
  • jbcs-httpd24-mod_jk jboss core services 1 1.2.50-18.redhat_1.el8jbcs
  • jbcs-httpd24-mod_md jboss core services 1 1:2.4.28-20.el8jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.62-17.el8jbcs
  • jbcs-httpd24-mod_ldap jboss core services 1 2.4.62-17.el8jbcs
  • jbcs-httpd24-mod_http2 jboss core services 1 2.0.29-14.el8jbcs
  • jbcs-httpd24-httpd-tools jboss core services 1 2.4.62-17.el8jbcs
  • jbcs-httpd24-mod_jk-ap24 jboss core services 1 1.2.50-18.redhat_1.el8jbcs

red hat advisories RHSA-2026:73076RHSA-2026:17080

  • apache2 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 2.4.66-150400.6.57.1
  • apache2 SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2-event SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2-utils SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2-manual SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2-worker SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2-prefork SLES 16.0, SLES for SAP applications 16.0 2.4.66-160000.2.1
  • apache2 SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.4.66-35.78.1

suse advisories SUSE-SU-2026:2641-1SUSE-SU-2026:2686-1SUSE-SU-2026:22199-1SUSE-SU-2026:22209-1

  • apache2 openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2-event openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2-utils openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2-manual openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2-worker openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2-prefork openSUSE Leap 16.0 2.4.66-160000.2.1
  • apache2 openSUSE Tumbleweed 2.4.67-1.1

opensuse advisories openSUSE-SU-2026:21115-1openSUSE-SU-2026:10785-1

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 2.4.67-r0

alpine advisories ALPINE-CVE-2026-33523

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 2.4.67-1

azure linux advisories AZL-86022

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-2026-33523 updated cvss 6.5

httpd: HTTP response splitting forwarding malicious status line

  • 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 Red Hat Enterprise Linux 8 httpd, mod_md, mod_ssl, mod_ldap, mod_http2, httpd-tools, +4 more Red Hat Enterprise Linux 9 httpd, mod_lua, mod_ssl, mod_ldap, httpd-core, httpd-tools, +4 more Red Hat Enterprise Linux 10 httpd
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images httpd 2.4.67-1.hum1, httpd-core 2.4.67-1.hum1, httpd-tools 2.4.67-1.hum1, httpd-manual 2.4.67-1.hum1, httpd-filesystem 2.4.67-1.hum1
    fixed: vendor fix RHSA-2026:17080
  • Red Hat JBoss Core Services 2.4.62.SP6
    fixed: vendor fix RHSA-2026:73077
  • Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.62-17.el8jbcs, jbcs-httpd24-mod_md 2.4.28-20.el8jbcs, jbcs-httpd24-mod_ssl 2.4.62-17.el8jbcs, jbcs-httpd24-mod_ldap 2.4.62-17.el8jbcs, jbcs-httpd24-mod_http2 2.0.29-14.el8jbcs, jbcs-httpd24-httpd-tools 2.4.62-17.el8jbcs, +8 more
    fixed: vendor fix RHSA-2026:73076
  • Red Hat Hardened Images mod_lua 2.4.67-1.hum1, mod_ssl 2.4.67-1.hum1, mod_ldap 2.4.67-1.hum1, mod_session 2.4.67-1.hum1, mod_proxy_html 2.4.67-1.hum1
    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
6 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% 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, <2.4.67
2.4.67

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

Weakness
  • CWE-443 DEPRECATED: HTTP response splitting
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.