CVE-2026-34441: Yhirose Cpp-Httplib

Medium severity, CVSS 6.5. EPSS: 0.3% 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 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.

Affected products

• Yhirose Cpp-Httplib: before 0.40.0 (fixed in 0.40.0)

Published 2026-03-31. Last modified 2026-07-24.