CVE-2026-34441 MEDIUM

CVE-2026-34441: cpp-httplib: HTTP Request Smuggling via Unconsumed GET Request Body

Vendor Yhirose
Product cpp-httplib
Weakness CWE-444
Published March 31, 2026
Last update April 1, 2026

CVSS base score

4.8/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 31, 2026 CVE published
April 1, 2026 Record updated