CVSS 4.0
7.7 highCVSS: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:PCVE-2026-21428
High (7.7) in yhirose cpp-httplib. EPSS 0.4% chance of exploitation in the next 30 days.
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
CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 34% of CVEs (scores of 2026-10-31)
- CWE
- CWE-93
- Published
- Modified
- Record from
- the NVD, synced
Affected
- yhirose:cpp-httplib