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CVE-2025-66570— cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)

Quick assessment

Affected
yhirose cpp-httplib
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

cpp-httplib是yhirose个人开发者的一款使用C++语言编写的HTTP/HTTPS服务器和客户端库。 cpp-httplib 0.27.0之前版本存在安全漏洞，该漏洞源于攻击者可控制的HTTP标头影响服务器可见的元数据、日志记录和授权决策，可能导致IP欺骗、日志投毒和授权绕过。

CVSS 10.0 · Critical EPSS 0.33% · P24
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I. Basic Information for CVE-2025-66570

Vulnerability Information
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Vulnerability Title
cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)
Source: CVE Program / CVE List V5
Vulnerability 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 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用欺骗进行的认证绕过
Source: CVE Program / CVE List V5
Vulnerability Title
cpp-httplib 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
cpp-httplib是yhirose个人开发者的一款使用C++语言编写的HTTP/HTTPS服务器和客户端库。 cpp-httplib 0.27.0之前版本存在安全漏洞，该漏洞源于攻击者可控制的HTTP标头影响服务器可见的元数据、日志记录和授权决策，可能导致IP欺骗、日志投毒和授权绕过。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
yhirose cpp-httplib < 0.27.0 -

II. Public POCs for CVE-2025-66570

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 7537 chars
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III. Intelligence Information for CVE-2025-66570

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Patches & Fixes for CVE-2025-66570 (1)

Vendor Advisories for CVE-2025-66570 (1)

IV. Related Vulnerabilities

Same product: cpp-httplib
Same vendor: yhirose
Same weakness: CWE-290

V. Comments for CVE-2025-66570

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