CVE-2026-46527
Severity CVSS v4.0:
HIGH
Type:
CWE-476
NULL Pointer Dereference
Publication date:
29/05/2026
Last modified:
29/05/2026
Description
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vector—undefined behavior in C++. On typical implementations this manifests as abnormal process termination (denial of service). With Sanitizers enabled, you get an explicit runtime diagnostic. This vulnerability is fixed in 0.44.0.
Impact
Base Score 4.0
8.70
Severity 4.0
HIGH