High severity7.5NVD Advisory· Published Jan 1, 2026· Updated Jun 17, 2026
CVE-2026-21428
CVE-2026-21428
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
4cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*+ 2 more
- cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*range: <0.30.0
- (no CPE)range: <0.30.0
- (no CPE)range: < 0.30.0
Patches
Vulnerability mechanics
References
3- github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcdnvdPatch
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-wpc6-j37r-jcx7nvdExploitThird Party Advisory
- github.com/yhirose/cpp-httplib/releases/tag/v0.30.0nvdProductRelease Notes
News mentions
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