{"id":"CVE-2025-66570","aliases":["DEBIAN-CVE-2025-66570","EUVD-2025-201455","GHSA-xm2j-vfr9-mg9m","OESA-2025-2854","OESA-2025-2855","OESA-2025-2856","OESA-2025-2857","OESA-2025-2858","SUSE-SU-2026:20090-1","UBUNTU-CVE-2025-66570","USN-7962-1","openSUSE-SU-2025:15844-1","openSUSE-SU-2026:20056-1"],"status":"published","title":"cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)","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.","severity":{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00348,"percentile":0.28722,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-290","CWE-345","CWE-807"],"published":"2025-12-05T18:18:02Z","modified":"2026-10-28T10:45:51Z","fixes":[{"ecosystem":"Debian:14","package":"cpp-httplib","fixed_in":["0.41.0+ds-3"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:22.04:LTS","package":"cpp-httplib","fixed_in":["0.10.3+ds-1ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:24.04:LTS","package":"cpp-httplib","fixed_in":["0.14.3+ds-1.1ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:25.10","package":"cpp-httplib","fixed_in":["0.18.7-1ubuntu0.25.10.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Debian:12","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.11.4+ds-1","0.11.4+ds-1+deb12u1","0.11.4+ds-2","0.11.4+ds-3","0.13.1+ds-1","0.14.0+ds-1","0.14.1+ds-1","0.14.1+ds-2","0.14.2+ds-1","0.14.3+ds-1","0.14.3+ds-1.1","0.14.3+ds-1.1~exp1","0.15.3+ds-1","0.15.3+ds-2","0.15.3+ds-3","0.16.0+ds-1","0.16.3+ds-1","0.16.3+ds-2","0.18.0+ds-1","0.18.7-1","0.20.1+ds-3","0.25.0+ds-1","0.26.0+ds-2","0.41.0+ds-1","0.41.0+ds-2","0.41.0+ds-3","0.41.0+ds-3~bpo13+1"]},{"source":"osv","ecosystem":"Debian:13","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.18.7-1","0.18.7-1+deb13u1","0.20.1+ds-3","0.25.0+ds-1","0.26.0+ds-2","0.41.0+ds-1","0.41.0+ds-2","0.41.0+ds-3","0.41.0+ds-3~bpo13+1"]},{"source":"osv","ecosystem":"Debian:14","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.41.0+ds-3"}]}],"versions":["0.18.7-1","0.20.1+ds-3","0.25.0+ds-1","0.26.0+ds-2","0.41.0+ds-1","0.41.0+ds-2","0.41.0+ds-3~bpo13+1"]},{"source":"osv","ecosystem":"openEuler:22.03-LTS-SP3","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.0-1.oe2203sp3"}]}],"bundled":2},{"source":"osv","ecosystem":"openEuler:22.03-LTS-SP4","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.0-1.oe2203sp4"}]}],"bundled":2},{"source":"osv","ecosystem":"openEuler:24.03-LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.0-1.oe2403"}]}],"bundled":2},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP1","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.0-1.oe2403sp1"}]}],"bundled":2},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP2","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.0-1.oe2403sp2"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 16.0","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0-160000.3.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0-160000.3.1"}]}],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.10.3+ds-1ubuntu0.1~esm1"}]}],"versions":["0.9.9+ds-1","0.9.10+ds-1","0.10.1+ds-1","0.10.2+ds-1","0.10.3+ds-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.14.3+ds-1.1ubuntu0.1~esm1"}]}],"versions":["0.13.1+ds-1ubuntu1","0.14.3+ds-1","0.14.3+ds-1.1","0.14.3+ds-1.1build1","0.14.3+ds-1.1build2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.18.7-1ubuntu0.25.10.1"}]}],"versions":["0.18.7-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.26.0+ds-2ubuntu3","0.26.0+ds-2ubuntu4"]},{"source":"osv","ecosystem":"Ubuntu:Pro:26.04:LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.18.7-1","0.26.0+ds-2ubuntu2","0.26.0+ds-2ubuntu3","0.26.0+ds-2ubuntu3+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.10.3+ds-1ubuntu0.1~esm1"}]}],"versions":["0.9.9+ds-1","0.9.10+ds-1","0.10.1+ds-1","0.10.2+ds-1","0.10.3+ds-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.14.3+ds-1.1ubuntu0.1~esm1"}]}],"versions":["0.13.1+ds-1ubuntu1","0.14.3+ds-1","0.14.3+ds-1.1","0.14.3+ds-1.1build1","0.14.3+ds-1.1build2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.18.7-1ubuntu0.25.10.1"}]}],"versions":["0.18.7-1"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.28.0-1.1"}]}],"bundled":2},{"source":"osv","ecosystem":"openSUSE:Leap 16.0","package":"cpp-httplib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.22.0-160000.3.1"}]}],"bundled":2}],"products":[{"vendor":"yhirose","product":"cpp-httplib"}],"references":[{"url":"https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xm2j-vfr9-mg9m","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory","report"]},{"url":"https://github.com/yhirose/cpp-httplib/commit/ac9ebb0ee333ce8bf13523f487bdfad9518a2aff","tags":["x_refsource_MISC","Patch","fix","report"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66570.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66570","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2025-66570","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2854","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66577","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2855","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2856","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2857","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2858","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202620090-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1254734","tags":["report"]},{"url":"https://bugzilla.suse.com/1254735","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2025-66570","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-66577","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2025-66570","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-66570","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-7962-1","tags":["advisory"]},{"url":"","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2025-66570","title":"cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)","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.","status":"published","published":"2025-12-05T18:18:02.928Z","modified":"2025-12-05T18:40:09.318Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical","assessor":"cna"}],"cwes":["CWE-290","CWE-345","CWE-807"],"updated_at":"2026-11-02T14:32:53.157279Z"}],"euvd":[{"id":"EUVD-2025-201455","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.","status":"published","published":"2025-12-05T18:18:02Z","modified":"2025-12-05T18:40:09Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T19:49:09.437744Z"}],"nvd":[{"id":"CVE-2025-66570","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.","status":"published","published":"2025-12-05T19:15:51.923Z","modified":"2026-06-17T09:57:02.887Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical","assessor":"secondary"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"}],"cwes":["CWE-290","CWE-345","CWE-807"],"updated_at":"2026-11-02T14:11:49.093461Z"}],"osv":[{"id":"CVE-2025-66570","title":"cpp-httplib Untrusted HTTP Header Handling: Internal Header Shadowing (REMOTE*/LOCAL*)","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.","status":"published","published":"2025-12-05T18:18:02.928Z","modified":"2026-10-28T10:45:51.894764488Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"cwes":["CWE-290","CWE-345","CWE-807"],"updated_at":"2026-11-02T15:44:52.202386Z"},{"id":"DEBIAN-CVE-2025-66570","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.","status":"published","published":"2025-12-05T19:15:51.923Z","modified":"2026-09-01T20:05:56.240606896Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:45:47.697959Z"},{"id":"OESA-2025-2854","title":"cpp-httplib security update","description":"A C++11 single-file header-only cross platform HTTP/HTTPS library. It\u0026amp;apos;s extremely easy to setup. Just include httplib.h file in your code!\r\n\r\nSecurity Fix(es):\n\ncpp-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.(CVE-2025-66570)\n\ncpp-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.(CVE-2025-66577)","status":"published","published":"2025-12-30T11:09:59Z","modified":"2026-08-18T01:19:23.764471615Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:52:45.339366Z"},{"id":"OESA-2025-2855","title":"cpp-httplib security update","description":"A C++11 single-file header-only cross platform HTTP/HTTPS library. It\u0026amp;apos;s extremely easy to setup. Just include httplib.h file in your code!\r\n\r\nSecurity Fix(es):\n\ncpp-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.(CVE-2025-66570)\n\ncpp-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.(CVE-2025-66577)","status":"published","published":"2025-12-30T11:09:59Z","modified":"2026-08-18T01:19:23.517913168Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:52:45.339366Z"},{"id":"OESA-2025-2856","title":"cpp-httplib security update","description":"A C++11 single-file header-only cross platform HTTP/HTTPS library. It\u0026amp;apos;s extremely easy to setup. Just include httplib.h file in your code!\r\n\r\nSecurity Fix(es):\n\ncpp-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.(CVE-2025-66570)\n\ncpp-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.(CVE-2025-66577)","status":"published","published":"2025-12-30T11:09:59Z","modified":"2026-08-18T01:19:23.53109398Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:52:45.339366Z"},{"id":"OESA-2025-2857","title":"cpp-httplib security update","description":"A C++11 single-file header-only cross platform HTTP/HTTPS library. It\u0026amp;apos;s extremely easy to setup. Just include httplib.h file in your code!\r\n\r\nSecurity Fix(es):\n\ncpp-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.(CVE-2025-66570)\n\ncpp-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.(CVE-2025-66577)","status":"published","published":"2025-12-30T11:09:59Z","modified":"2026-08-18T01:19:23.865140743Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:52:45.339366Z"},{"id":"OESA-2025-2858","title":"cpp-httplib security update","description":"A C++11 single-file header-only cross platform HTTP/HTTPS library. It\u0026amp;apos;s extremely easy to setup. Just include httplib.h file in your code!\r\n\r\nSecurity Fix(es):\n\ncpp-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.(CVE-2025-66570)\n\ncpp-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.(CVE-2025-66577)","status":"published","published":"2025-12-30T11:09:59Z","modified":"2026-08-18T01:19:23.897867951Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"}],"updated_at":"2026-11-02T15:52:45.339366Z"},{"id":"UBUNTU-CVE-2025-66570","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.","status":"published","published":"2025-12-05T19:15:00Z","modified":"2026-10-17T12:57:37.500586521Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"critical"},{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T16:55:52.345622Z"},{"id":"openSUSE-SU-2025:15844-1","title":"cpp-httplib-devel-0.28.0-1.1 on GA media","description":"These are all security issues fixed in the cpp-httplib-devel-0.28.0-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2025-12-24T00:00:00Z","modified":"2026-03-23T04:54:14.358768Z","updated_at":"2026-11-02T16:58:38.101535Z"},{"id":"openSUSE-SU-2026:20056-1","title":"Security update for cpp-httplib","description":"This update for cpp-httplib fixes the following issues:\n\n- CVE-2025-66570: IP spoofing, log poisoning, and authorization bypass via header shadowing due to acceptance and\n  parsing of client-controlled injected HTTP headers in incoming requests (bsc#1254734).\n- CVE-2025-66577: access and error log poisoning with spoofed client IPs due to unconditional acceptance of\n  client-controlled `X-Forwarded-For` and `X-Real-IP` headers (bsc#1254735).\n","status":"published","published":"2026-01-15T22:11:25Z","modified":"2026-03-23T04:54:42.806038Z","updated_at":"2026-11-02T16:58:41.463445Z"},{"id":"SUSE-SU-2026:20090-1","title":"Security update for cpp-httplib","description":"This update for cpp-httplib fixes the following issues:\n\n- CVE-2025-66570: IP spoofing, log poisoning, and authorization bypass via header shadowing due to acceptance and\n  parsing of client-controlled injected HTTP headers in incoming requests (bsc#1254734).\n- CVE-2025-66577: access and error log poisoning with spoofed client IPs due to unconditional acceptance of\n  client-controlled `X-Forwarded-For` and `X-Real-IP` headers (bsc#1254735).\n","status":"published","published":"2026-01-15T22:11:51Z","modified":"2026-03-23T04:52:34.721453Z","updated_at":"2026-11-02T15:54:01.610851Z"},{"id":"USN-7962-1","title":"cpp-httplib vulnerability","description":"It was discovered that cpp-httplib did not correctly handle  HTTP headers.\nA remote attacker could possibly use this  issue to bypass authorization\nand impersonate users.","status":"published","published":"2026-01-14T16:22:23Z","modified":"2026-04-27T18:32:44.899577Z","updated_at":"2026-11-02T16:58:21.91885Z"}]}}