CVE-2026-29076: Yhirose Cpp-Httplib

Medium severity, CVSS 5.9. EPSS: 0.6% 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 0.37.0, cpp-httplib uses std::regex (libstdc++) to parse RFC 5987 encoded filename* values in multipart Content-Disposition headers. The regex engine in libstdc++ implements backtracking via deep recursion, consuming one stack frame per input character. An attacker can send a single HTTP POST request with a crafted filename* parameter that causes uncontrolled stack growth, resulting in a stack overflow (SIGSEGV) that crashes the server process. This issue has been patched in version 0.37.0.

Affected products

• Yhirose Cpp-Httplib: before 0.37.0 (fixed in 0.37.0)

Published 2026-03-07. Last modified 2026-06-17.