Vulnerability in Yhirose Cpp-Httplib
CVE-2026-34441
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.
Vulnerability class: HTTP Request Smuggling
EPSS: 0.002 (9.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Yhirose Cpp-httplib — versions < 0.40.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-34441?
- CVE-2026-34441 is a medium-severity vulnerability in Yhirose Cpp-Httplib, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 4.8/10. Published 2026-03-31.
- How severe is CVE-2026-34441?
- Medium severity. CVSS v3 base score is 4.8 out of 10.