CVE-2025-66570
CriticalSummary
cpp-httplib prior to 0.27.0 has a vulnerability that 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, and the server later appends its own internal metadata without erasing duplicates, potentially leading to the use of attacker-controlled values.
Risk Assessment
An attacker can manipulate IP address and port information, potentially affecting logs, authorization, and other decisions based on this data, possibly leading to unauthorized access.
Recommendation
Update cpp-httplib to version 0.27.0 or later. Additionally, consider filtering or removing client-supplied headers that may conflict with internal metadata.
Original NVD description (English source)
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