cpp-httplib has CRLF injection in http headers_CVE-2026-21428

7.7 / 10

HIGH

CVSS: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

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.

Basic Information

ID CVE-2026-21428

Source GitHub_M

Published Jan 1, 2026 at 17:54

Affected Product

Vendor yhirose

Product cpp-httplib

Version < 0.30.0

Affected Versions yhirose cpp-httplib < 0.30.0

CWE Classification

CWE-93

References

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    "published": "2026-01-01T17:54:43.959Z",
    "modified": "2026-01-01T17:54:43.959Z",
    "type": "cve",
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