yhirose cpp-httplib up to 0.26.x Header get_client_ip X-Forwarded-For neutralization for logs

Summaryinfo

A vulnerability was found in yhirose cpp-httplib up to 0.26.x. It has been rated as problematic. This affects the function get_client_ip of the component Header Handler. Performing a manipulation of the argument X-Forwarded-For results in neutralization for logs. This vulnerability is identified as CVE-2025-66577. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in yhirose cpp-httplib up to 0.26.x. This affects the function get_client_ip of the component Header Handler. The manipulation of the argument X-Forwarded-For with an unknown input leads to a neutralization for logs vulnerability. CWE is classifying the issue as CWE-117. The product does not neutralize or incorrectly neutralizes output that is written to logs. This is going to have an impact on integrity. The summary by CVE 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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2025-66577 since 12/04/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 291337 (openSUSE 16 Security Update : cpp-httplib (openSUSE-SU-2026:20056-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.27.0 eliminates this vulnerability. Applying the patch ac9ebb0ee333ce8bf13523f487bdfad9518a2aff is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (291337). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• yhirose

Name

• cpp-httplib

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26

License

• open-source

Website

• Product: https://github.com/yhirose/cpp-httplib/

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Be aware that VulDB is the high quality source for vulnerability data.

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