cvedb.io
CVE-2026-21428
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2026-01-01T18:15:41.057 · Last modified 2026-06-17T10:18:39.177

Summary

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.

Affected products

yhirose — cpp-httplib

Does this affect you?

Add your gear to cvedb and we'll alert you only when yhirose ships something exploited.

Check my exposure →

References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.