CVE-2026-21428 | THREATINT

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.

PUBLISHED Reserved 2025-12-29 | Published 2026-01-01 | Updated 2026-01-02 | Assigner GitHub_M

HIGH: 7.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Problem types

CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

Product status

< 0.30.0

affected

References

github.com/...ttplib/security/advisories/GHSA-wpc6-j37r-jcx7

github.com/...ommit/98048a033a532ff22320ce1d11789f8d5710dfcd

github.com/yhirose/cpp-httplib/releases/tag/v0.30.0

cve.org (CVE-2026-21428)

nvd.nist.gov (CVE-2026-21428)

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