CVE-2025-66577

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

State: Published
Severity: 5.3 Medium
Published: Dec 5, 2025
Updated: Dec 5, 2025
Reserved: Dec 4, 2025

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N	GitHub_M

Weaknesses

CWE-117 Improper Output Neutralization for Logs
CWE-807 Reliance on Untrusted Inputs in a Security Decision

Affected Products

Product	Versions
cpp-httplibyhirose	< 0.27.0Affected

References

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