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Fencer Vulns
medium 5.3

CVE-2026-33857 json

Apache HTTP Server: Off-by-one OOB reads in AJP getter functions

published 2026-05-04 6 mo ago modified 2026-10-26 13 d ago also BIT-apache-2026-33857 , EUVD-2026-26951

cvss
5.3
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 33%
public exploits
0
none known

Summary

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.

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-2026-33857

  • 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-2026-33857

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 2.4.62-13.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.62-13.el8jbcs
  • jbcs-httpd24-mod_md jboss core services 1 1:2.4.28-16.el7jbcs
  • jbcs-httpd24-mod_md jboss core services 1 1:2.4.28-16.el8jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.62-13.el7jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.62-13.el8jbcs
  • jbcs-httpd24-nghttp2 jboss core services 1 1.64.0-3.el7jbcs
  • jbcs-httpd24-nghttp2 jboss core services 1 1.64.0-3.el8jbcs

red hat advisories RHSA-2026:67152RHSA-2026:66323RHSA-2026:62165RHSA-2026:47046RHSA-2026:36846RHSA-2026:36831

  • 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

  • httpd AlmaLinux 8 2.4.37-65.module_el8.10.0+4185+0955a0d7.8
  • 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+4185+0955a0d7.8
  • mod_ldap AlmaLinux 8 2.4.37-65.module_el8.10.0+4185+0955a0d7.8
  • mod_http2 AlmaLinux 8 1.15.7-10.module_el8.10.0+4185+0955a0d7.5
  • httpd-tools AlmaLinux 8 2.4.37-65.module_el8.10.0+4185+0955a0d7.8
  • mod_session AlmaLinux 8 2.4.37-65.module_el8.10.0+4185+0955a0d7.8
  • httpd-manual AlmaLinux 8 2.4.37-65.module_el8.10.0+4185+0955a0d7.8

almalinux advisories ALSA-2026:22140ALSA-2026:21391ALSA-2026:21433

  • httpd Rocky Linux 10 2.4.63-13.el10_2.1
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+2061+8d03fdec.5
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1830+22f0c9e0
  • 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+1984+1bed3124.4
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1842+4a9649e8.2
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1840+b070a976.1
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+40053+5a18018e.7

rocky linux advisories RLSA-2026:21433RLSA-2026:22140RLSA-2026:21391

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

alpine advisories ALPINE-CVE-2026-33857

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-86007

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-2026-33857 updated cvss 7.5

httpd: mod_proxy_ajp: off-by-one out-of-bounds reads in AJP getter functions

  • Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual
    affected: workaround, no fix available “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.”
  • 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+24281+ea10630c.8, mod_ssl 2.4.37-65.module+el8.10.0+24281+ea10630c.8, mod_ldap 2.4.37-65.module+el8.10.0+24281+ea10630c.8, mod_http2 1.15.7-10.module+el8.10.0+24315+35fe59d0.5, httpd-tools 2.4.37-65.module+el8.10.0+24281+ea10630c.8, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:22140
  • Red Hat Enterprise Linux AppStream (v. 9) httpd 2.4.62-13.el9_8.1, mod_lua 2.4.62-13.el9_8.1, mod_ssl 2.4.62-13.el9_8.1, mod_ldap 2.4.62-13.el9_8.1, httpd-core 2.4.62-13.el9_8.1, httpd-tools 2.4.62-13.el9_8.1, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:21391
  • Red Hat Enterprise Linux AppStream (v. 10) httpd 2.4.63-13.el10_2.1, mod_lua 2.4.63-13.el10_2.1, mod_ssl 2.4.63-13.el10_2.1, mod_ldap 2.4.63-13.el10_2.1, httpd-core 2.4.63-13.el10_2.1, httpd-tools 2.4.63-13.el10_2.1, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:21433
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) mod_md 2.0.8-8.module+el8.4.0+23842+00253415.1, httpd 2.4.37-39.module+el8.4.0+24495+1afced82.12, mod_http2 1.15.7-3.module+el8.4.0+24495+1afced82.5, mod_ssl 2.4.37-39.module+el8.4.0+24495+1afced82.12, mod_ldap 2.4.37-39.module+el8.4.0+24495+1afced82.12, httpd-tools 2.4.37-39.module+el8.4.0+24495+1afced82.12, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36846
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) mod_md 2.0.8-8.module+el8.6.0+23843+c27a5dc4.1, httpd 2.4.37-47.module+el8.6.0+24496+af8fe930.13, mod_http2 1.15.7-5.module+el8.6.0+24496+af8fe930.5, mod_ssl 2.4.37-47.module+el8.6.0+24496+af8fe930.13, mod_ldap 2.4.37-47.module+el8.6.0+24496+af8fe930.13, httpd-tools 2.4.37-47.module+el8.6.0+24496+af8fe930.13, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36831
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) mod_md 2.0.8-8.module+el8.8.0+23840+d7e7db80.1, httpd 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, mod_http2 1.15.7-8.module+el8.8.0+24497+e470c0e2.7, mod_ssl 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, mod_ldap 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, httpd-tools 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36373
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) httpd 2.4.53-11.el9_2.15, httpd-core 2.4.53-11.el9_2.15
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:67152
show 11 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) httpd 2.4.57-11.el9_4.5, httpd-core 2.4.57-11.el9_4.5
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:66323
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) httpd 2.4.63-1.el10_0.4, mod_lua 2.4.63-1.el10_0.4, mod_ssl 2.4.63-1.el10_0.4, mod_ldap 2.4.63-1.el10_0.4, httpd-core 2.4.63-1.el10_0.4, httpd-tools 2.4.63-1.el10_0.4, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:47046
  • 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, httpd-core 2.4.62-4.el9_6.6, httpd-tools 2.4.62-4.el9_6.6, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:62165
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) mod_md 2.0.8-8.module+el8.4.0+23842+00253415.1, httpd 2.4.37-39.module+el8.4.0+24495+1afced82.12, mod_http2 1.15.7-3.module+el8.4.0+24495+1afced82.5, mod_ssl 2.4.37-39.module+el8.4.0+24495+1afced82.12, mod_ldap 2.4.37-39.module+el8.4.0+24495+1afced82.12, httpd-tools 2.4.37-39.module+el8.4.0+24495+1afced82.12, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36846
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) mod_md 2.0.8-8.module+el8.6.0+23843+c27a5dc4.1, httpd 2.4.37-47.module+el8.6.0+24496+af8fe930.13, mod_http2 1.15.7-5.module+el8.6.0+24496+af8fe930.5, mod_ssl 2.4.37-47.module+el8.6.0+24496+af8fe930.13, mod_ldap 2.4.37-47.module+el8.6.0+24496+af8fe930.13, httpd-tools 2.4.37-47.module+el8.6.0+24496+af8fe930.13, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36831
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) mod_md 2.0.8-8.module+el8.8.0+23840+d7e7db80.1, httpd 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, mod_http2 1.15.7-8.module+el8.8.0+24497+e470c0e2.7, mod_ssl 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, mod_ldap 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, httpd-tools 2.4.37-56.module+el8.8.0+24497+e470c0e2.12, +4 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:36373
  • Red Hat Enterprise Linux Server (v. 7 ELS) httpd 2.4.6-99.el7_9.8 Red Hat Enterprise Linux Server Optional (v. 7 ELS) httpd-debuginfo 2.4.6-99.el7_9.8
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:92590
  • Red Hat Hardened Images httpd 2.4.67-0.1.hum1, httpd-core 2.4.67-0.1.hum1, httpd-tools 2.4.67-0.1.hum1, httpd-manual 2.4.67-0.1.hum1, httpd-filesystem 2.4.67-0.1.hum1
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:13938
  • Red Hat JBoss Core Services 2.4.62.SP4
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:27201
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-httpd 2.4.62-13.el7jbcs, jbcs-httpd24-mod_ssl 2.4.62-13.el7jbcs, jbcs-httpd24-mod_ldap 2.4.62-13.el7jbcs, jbcs-httpd24-httpd-tools 2.4.62-13.el7jbcs, jbcs-httpd24-mod_session 2.4.62-13.el7jbcs, jbcs-httpd24-httpd-manual 2.4.62-13.el7jbcs, +2 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.62-13.el8jbcs, jbcs-httpd24-mod_ssl 2.4.62-13.el8jbcs, jbcs-httpd24-mod_ldap 2.4.62-13.el8jbcs, jbcs-httpd24-httpd-tools 2.4.62-13.el8jbcs, jbcs-httpd24-mod_session 2.4.62-13.el8jbcs, jbcs-httpd24-httpd-manual 2.4.62-13.el8jbcs, +2 more
    fixed: vendor fix “Disabling mod_proxy_ajp and restarting httpd will mitigate this flaw.” RHSA-2026:27200
  • 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 Server (v. 7 ELS) mod_ssl 2.4.6-99.el7_9.8, httpd-tools 2.4.6-99.el7_9.8, mod_session 2.4.6-99.el7_9.8, httpd-manual 2.4.6-99.el7_9.8 Red Hat Enterprise Linux Server Optional (v. 7 ELS) mod_ldap 2.4.6-99.el7_9.8, mod_proxy_html 2.4.6-99.el7_9.8 Red Hat Hardened Images mod_lua 2.4.67-0.1.hum1, mod_ssl 2.4.67-0.1.hum1, mod_ldap 2.4.67-0.1.hum1, mod_session 2.4.67-0.1.hum1, mod_proxy_html 2.4.67-0.1.hum1 Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-mod_md 2.4.28-16.el7jbcs, jbcs-httpd24-nghttp2 1.64.0-3.el7jbcs, jbcs-httpd24-mod_http2 2.0.29-10.el7jbcs, jbcs-httpd24-mod_security 2.9.6-16.el7jbcs, jbcs-httpd24-mod_jk 1.2.50-14.redhat_1.el7jbcs, jbcs-httpd24-mod_proxy_cluster 1.3.22-9.el7jbcs, +1 more
    +1 more products
    Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-mod_md 2.4.28-16.el8jbcs, jbcs-httpd24-nghttp2 1.64.0-3.el8jbcs, jbcs-httpd24-mod_http2 2.0.29-10.el8jbcs, jbcs-httpd24-mod_security 2.9.6-16.el8jbcs, jbcs-httpd24-mod_jk 1.2.50-14.redhat_1.el8jbcs, jbcs-httpd24-mod_proxy_cluster 1.3.22-9.el8jbcs, +1 more
    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

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
bitnami apache
<2.4.67
2.4.67

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.