CVE-2026-21428 is a high severity vulnerability with a CVSS score of 7.5. Exploits are available; patches have been released and should be applied urgently.
Very low probability of exploitation
EPSS predicts the probability of exploitation in the next 30 days based on real-world threat data, complementing CVSS severity scores with actual risk assessment.
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.
| Vendor | Product |
|---|---|
| Yhirose | Cpp Httplib |
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