CVE-2026-21428

unknown

Published — · Modified —

CVSS v3

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CVSS v2

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VIR risk

—

Description

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.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2026-21428.html

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2026-21428

OS impact

OS	Version	Status	Fixed in
debian	bookworm	affected
debian	forky	fixed	`0.41.0+ds-3`
debian	sid	fixed	`0.41.0+ds-3`
debian	trixie	affected
sles		affected

References

Verify integrity in audit chain (admin only). AS-IS.