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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (18.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Yhirose Cpp-Httplib — versions < 0.40.0
Weakness classification (CWE)
References
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-jv63-rm9j-6jwc (Exploit, Mitigation, Vendor Advisory)
- github.com/yhirose/cpp-httplib/releases/tag/v0.40.0 (Product, 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.