CVE-2025-66577 MEDIUM

CVE-2025-66577: cpp-httplib Untrusted HTTP Header Handling: X-Forwarded-For/X-Real-IP Trust

Vendor Yhirose
Product cpp-httplib
Weakness CWE-117
Published December 5, 2025
Last update December 5, 2025

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 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.

Key dates

02Disclosure timeline

December 5, 2025 CVE published
December 5, 2025 Record updated