CVE-2026-21428

high

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.

References

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-wpc6-j37r-jcx7

https://github.com/yhirose/cpp-httplib/releases/tag/v0.30.0

https://github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcd

Details

Source: Mitre, NVD

Published: 2026-01-01

Updated: 2026-01-02

Risk Information

CVSS v2

Base Score: 6.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N

Severity: Medium

CVSS v3

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Severity: High

CVSS v4

Base Score: 8.7

Vector: 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

Severity: High

EPSS

EPSS: 0.00045