Bug 2426666 (CVE-2026-21428)

Summary:	CVE-2026-21428 cpp-httplib: cpp-httplib: Server-Side Request Forgery via header injection
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in cpp-httplib, a C++ HTTP/HTTPS library. A remote attacker can exploit this vulnerability by injecting carriage return and line feed characters into user-supplied headers. This allows the attacker to add extra headers, modify the request body, and potentially trigger a Server-Side Request Forgery attack, which can be used to make a server send requests to an unintended location.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Bug Depends On:	2426696, 2426697, 2426698, 2426699, 2426700
Bug Blocks:

Description OSIDB Bzimport 2026-01-01 18:01:20 UTC

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines.
This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.