Apache HTTP Server 2.4.66 Response Splitting via Modules
CVE-2026-33523 Published on May 4, 2026
Apache HTTP Server: multiple modules: HTTP response splitting forwarding malicious status line
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.
Vulnerability Analysis
CVE-2026-33523 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Timeline
reported
2.4.67 released 60 days later.
fixed in 2.4.x by r1933360
Weakness Type
DEPRECATED (Duplicate): HTTP response splitting
This weakness can be found at CWE-113.
Products Associated with CVE-2026-33523
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Affected Versions
Apache Software Foundation Apache HTTP Server:- Version 2.4.0, <= 2.4.66 is affected.