Bug 2412046 (CVE-2025-12642)

Summary:	CVE-2025-12642 lighthttpd: HTTP Header Smuggling via Trailer Merge
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2412439, 2412440, 2412441
Bug Blocks:

Description OSIDB Bzimport 2025-11-03 20:03:44 UTC

lighttpd1.4.80 incorrectly merged trailer fields into headers after http request parsing. This behavior can be exploited to conduct HTTP Header Smuggling attacks.

Successful exploitation may allow an attacker to:

  *  Bypass access control rules
  *  Inject unsafe input into backend logic that trusts request headers
  *  Execute HTTP Request Smuggling attacks under some conditions


This issue affects lighttpd1.4.80