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CVE

CVE-2026-33523

HTTP response splitting vulnerability in multiple Apache HTTP Server modules with untrusted or compromised backend serve

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.

MEDIUM · CVSS 6.5 EPSS 0.00259
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-443DEPRECATED: HTTP response splitting
▤

Affected Products & Versions

1
apache http server>= 2.4.0 and < 2.4.67
▣

Scoring & Timeline

6.5
MEDIUM · CVSS v3.1 · security@apache.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD04 May 2026 · 03:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

5
suse-csafopenSUSE-SU-2026:10785-1
msrcCVE-2026-33523
usnUSN-8239-1
rhsaRHSA-2026:17080Low
oracle-cpuoracle-cpu-Oracle-Communications-Unified-Assurance-14597--CVE-2026-33523
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://httpd.apache.org/security/vulnerabilities_24.htmlVendor Advisory
http://www.openwall.com/lists/oss-security/2026/05/04/23Mailing ListThird Party Advisory
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