CVE-2026-33523
Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line
CVE-2026-33523 is fixed in 33 products on 1 platform, first by apache2 2.4.66-2ubuntu2.1, released May 4, 2026. It is not reported as exploited. Patch Radar priority: Routine.
Routine
CVSS
6.5
Moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0044
38th percentile
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| apache2 · Debian 12.15 (bookworm) | 2.4.67-1~deb12u2 | DEBIAN-CVE-2026-33523 | May 15, 2026 |
| apache2 · Debian 13.5 (trixie) | 2.4.67-1~deb13u2 | DEBIAN-CVE-2026-33523 | May 15, 2026 |
| apache2 · Debian 14 | 2.4.67-1 | DEBIAN-CVE-2026-33523 | May 15, 2026 |
| apache2 · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2 · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2 · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2 · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2 · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2 · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2 · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2 · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-bin · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2-bin 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2-bin · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2-bin 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2-bin · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2-bin 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2-bin · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2-bin 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2-bin · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2-bin 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2-bin · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2-bin 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2-data · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2-data 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2-data · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2-data 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2-data · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2-data 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2-data · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2-data 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2-data · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2-data 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2-data · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2-data 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2-devel · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-devel · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-event · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-event · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-manual · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-manual · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-prefork · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-prefork · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-suexec-custom · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2-suexec-custom 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2-suexec-custom · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2-suexec-custom 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2-suexec-custom · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2-suexec-custom 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2-suexec-custom · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2-suexec-custom 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2-suexec-custom · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2-suexec-custom 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2-suexec-custom · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2-suexec-custom 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2-suexec-pristine · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2-suexec-pristine 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2-suexec-pristine · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2-suexec-pristine 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2-suexec-pristine · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2-suexec-pristine 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2-suexec-pristine · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2-suexec-pristine 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2-suexec-pristine · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2-suexec-pristine 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2-suexec-pristine · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2-suexec-pristine 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2-utils · Ubuntu 18.04.6 LTS (bionic) | 2.4.29-1ubuntu4.27+esm10 | apache2-utils 2.4.29-1ubuntu4.27+esm10 | Jun 8, 2026 |
| apache2-utils · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | apache2-utils 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| apache2-utils · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | apache2-utils 2.4.52-1ubuntu4.20 | May 15, 2026 |
| apache2-utils · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | apache2-utils 2.4.58-1ubuntu8.12 | May 15, 2026 |
| apache2-utils · Ubuntu 25.10 (questing) | 2.4.64-1ubuntu3.4 | apache2-utils 2.4.64-1ubuntu3.4 | May 15, 2026 |
| apache2-utils · Ubuntu 26.04.1 LTS (resolute) | 2.4.66-2ubuntu2.1 | apache2-utils 2.4.66-2ubuntu2.1 | May 4, 2026 |
| apache2-utils · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-utils · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| apache2-worker · opensuse-leap 16.0 | 2.4.66-160000.2.1 | OPENSUSE-SU-2026:21115-1 | Jun 20, 2026 |
| apache2-worker · sles 16.0 | 2.4.66-160000.2.1 | SUSE-SU-2026:22209-1 | Jun 20, 2026 |
| httpd · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-core · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-core-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-debugsource · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-devel · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-filesystem · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-manual · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-tools · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| httpd-tools-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| libapache2-mod-md · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | libapache2-mod-md 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| libapache2-mod-md · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | libapache2-mod-md 2.4.52-1ubuntu4.20 | May 15, 2026 |
| libapache2-mod-md · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | libapache2-mod-md 2.4.58-1ubuntu8.12 | May 15, 2026 |
| libapache2-mod-proxy-uwsgi · Ubuntu 20.04 LTS (focal) | 2.4.41-4ubuntu3.23+esm5 | libapache2-mod-proxy-uwsgi 2.4.41-4ubuntu3.23+esm5 | Jun 8, 2026 |
| libapache2-mod-proxy-uwsgi · Ubuntu 22.04.1 LTS (jammy) | 2.4.52-1ubuntu4.20 | libapache2-mod-proxy-uwsgi 2.4.52-1ubuntu4.20 | May 15, 2026 |
| libapache2-mod-proxy-uwsgi · Ubuntu 24.04.5 LTS (noble) | 2.4.58-1ubuntu8.12 | libapache2-mod-proxy-uwsgi 2.4.58-1ubuntu8.12 | May 15, 2026 |
| mod_ldap · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_ldap-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_lua · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_lua-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_proxy_html · amzn 2023 | 1:2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_proxy_html-debuginfo · amzn 2023 | 1:2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_session · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_session-debuginfo · amzn 2023 | 2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_ssl · amzn 2023 | 1:2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
| mod_ssl-debuginfo · amzn 2023 | 1:2.4.67-1.amzn2023.0.1 | ALAS2023-2026-1720 | May 25, 2026 |
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