CVE-2025-66577: Yhirose Cpp-Httplib

Medium severity, CVSS 5.3. 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 0.27.0, a vulnerability allows attacker-controlled HTTP headers to influence server-visible metadata, logging, and authorization decisions. An attacker can supply X-Forwarded-For or X-Real-IP headers which get accepted unconditionally by get_client_ip() in docker/main.cc, causing access and error logs (nginx_access_logger / nginx_error_logger) to record spoofed client IPs (log poisoning / audit evasion). This vulnerability is fixed in 0.27.0.

Affected products

• Yhirose Cpp-Httplib: before 0.27.0 (fixed in 0.27.0)

Published 2025-12-05. Last modified 2026-06-17.