CVE-2026-21428 – cpp-httplib has CRLF injection in http headers

CVE ID : CVE-2026-21428

Published : Jan. 1, 2026, 5:54 p.m. | 30 minutes ago

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.

Severity: 0.0 | NA

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