EUVD-2025-201455CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Lifecycle Timeline
5Description
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 inject headers named REMOTE_ADDR, REMOTE_PORT, LOCAL_ADDR, LOCAL_PORT that are parsed into the request header multimap via read_headers() in httplib.h (headers.emplace), then the server later appends its own internal metadata using the same header names in Server::process_request without erasing duplicates. Because Request::get_header_value returns the first entry for a header key (id == 0) and the client-supplied headers are parsed before server-inserted headers, downstream code that uses these header names may inadvertently use attacker-controlled values. Affected files/locations: cpp-httplib/httplib.h (read_headers, Server::process_request, Request::get_header_value, get_header_value_u64) and cpp-httplib/docker/main.cc (get_client_ip, nginx_access_logger, nginx_error_logger). Attack surface: attacker-controlled HTTP headers in incoming requests flow into the Request.headers multimap and into logging code that reads forwarded headers, enabling IP spoofing, log poisoning, and authorization bypass via header shadowing. This vulnerability is fixed in 0.27.0.
Analysis
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 inject headers named REMOTE_ADDR, REMOTE_PORT, LOCAL_ADDR, LOCAL_PORT that are parsed into the request header multimap via read_headers() in httplib.h (headers.emplace), then the server later appends its own internal metadata using the same header names in Server::process_request without erasing duplicates. Because Request::get_header_value returns the first entry for a header key (id == 0) and the client-supplied headers are parsed before server-inserted headers, downstream code that uses these header names may inadvertently use attacker-controlled values. Affected files/locations: cpp-httplib/httplib.h (read_headers, Server::process_request, Request::get_header_value, get_header_value_u64) and cpp-httplib/docker/main.cc (get_client_ip, nginx_access_logger, nginx_error_logger). Attack surface: attacker-controlled HTTP headers in incoming requests flow into the Request.headers multimap and into logging code that reads forwarded headers, enabling IP spoofing, log poisoning, and authorization bypass via header shadowing. This vulnerability is fixed in 0.27.0.
Technical Context
An authentication bypass vulnerability allows attackers to circumvent login mechanisms and gain unauthorized access without valid credentials. This vulnerability is classified as Authentication Bypass by Spoofing (CWE-290).
Affected Products
Affected products: Yhirose Cpp-Httplib
Remediation
A vendor patch is available — apply it immediately. Implement robust authentication mechanisms. Use multi-factor authentication. Review authentication logic for bypass conditions. Remove default credentials.
Priority Score
Vendor Status
Ubuntu
Priority: High| Release | Status | Version |
|---|---|---|
| jammy | released | 0.10.3+ds-1ubuntu0.1~esm1 |
| noble | released | 0.14.3+ds-1.1ubuntu0.1~esm1 |
| plucky | released | 0.18.7-1ubuntu0.25.04.1 |
| questing | released | 0.18.7-1ubuntu0.25.10.1 |
| upstream | released | 0.27.0 |
Debian
Bug #1122027| Release | Status | Fixed Version | Urgency |
|---|---|---|---|
| bookworm | vulnerable | 0.11.4+ds-1+deb12u1 | - |
| forky, sid, trixie | vulnerable | 0.18.7-1 | - |
| (unstable) | fixed | (unfixed) | - |
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External POC / Exploit Code
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