CVE-2025-66577CWE-117CWE-807

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

Medium · published December 5, 2025

CVSS v3.1
5.3
EPSS
0%
Percentile
18.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00274 · 18.8th percentile
Weaknesses
CWE-117 · Improper Output Neutralization for Logs; CWE-807 · Reliance on Untrusted Inputs in a Security Decision
Published
2025-12-05T18:20Z
EPSS history
Timeline
  • 05 DEC 18:20Z
    cpp-httplib Untrusted HTTP Header Handling: X-Forwarded-For/X-Real-IP Trust
    cvelistv5