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.
How to fix
- yhirose cpp-httplib0.30.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| yhirose cpp-httplib | v < 0.30.0 | 0.30.0 |
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