{"id":"CVE-2026-46527","summary":"cpp-httplib: Malicious `X-Forwarded-For` Under Trusted-Proxy Configuration Triggers Empty `vector::front()`, Leading to Undefined Behavior and Server Crash","details":"cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, When the server has called Server::set_trusted_proxies() with a non-empty trusted-proxy list, an attacker can send an HTTP request that includes an X-Forwarded-For header whose value parses to no valid IP segments. The code path then executes get_client_ip(), which calls front() on an empty std::vector—undefined behavior in C++. On typical implementations this manifests as abnormal process termination (denial of service). With Sanitizers enabled, you get an explicit runtime diagnostic. This vulnerability is fixed in 0.44.0.","aliases":["GHSA-hg3g-vrg8-578g"],"modified":"2026-08-12T03:51:44.290938501Z","published":"2026-05-29T19:18:26.615Z","related":["openSUSE-SU-2026:10994-1"],"database_specific":{"cwe_ids":["CWE-476"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46527.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46527.json"},{"type":"ADVISORY","url":"https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-hg3g-vrg8-578g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46527"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/yhirose/cpp-httplib","events":[{"introduced":"0"},{"fixed":"811dd0b6f2382f50f801f3cfdb5ba349d08bb575"}],"database_specific":{"source":["AFFECTED_FIELD","CPE_RANGE"],"cpe":"cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"0.44.0"}]}}],"versions":["v0.43.4","v0.43.3","v0.43.2","v0.43.1","v0.43.0","v0.42.0","v0.41.0","v0.40.0","v0.39.0","v0.38.0","v0.37.2","v0.37.1","v0.37.0","v0.35.0","v0.34.0","latest","v0.33.1","v0.33.0","v0.32.0","v0.31.0","v0.30.2","v0.30.1","v0.30.0","v0.29.0","v0.28.0","v0.27.0","v0.26.0","v0.25.0","v0.24.0","v0.23.1","v0.23.0","v0.22.0","v0.21.0","v0.20.1","v0.20.0","v0.19.0","v0.18.7","v0.18.6","v0.18.5","v0.18.4","v0.18.3","v0.18.2","v0.18.1","v0.18.0","v0.17.3","v0.17.2","v0.17.1","v0.17.0","v0.16.3","v0.16.2","v0.16.1","v0.16.0","v0.15.3","v0.15.2","v0.15.1","v0.15.0","v0.14.3","v0.14.2","v0.14.1","v0.14.0","v0.13.3","v0.13.2","v0.13.1","v0.13.0","v0.12.6","v0.12.5","v0.12.4","v0.12.3","v0.12.2","v0.12.1","v0.12.0","v0.11.4","v0.11.3","v0.11.2","v0.11.1","v0.11.0","v0.10.9","v0.10.8","v0.10.7","v0.10.6","v0.10.5","v0.10.4","v0.10.3","v0.10.2","v0.10.1","v0.10.0","v0.9.10","v0.9.9","v0.9.8","v0.9.7","v0.9.6","v0.9.5","v0.9.4","v0.9.3","v0.9.2","v0.9.1","v0.9.0","v0.8.9","v0.8.8","v0.8.7","v0.8.6","v0.8.5","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8.0","v0.7.18","v0.7.17","v0.7.16","v0.7.15","v0.7.14","v0.7.13","v0.7.12","v0.7.11","v0.7.10","v0.7.9","v0.7.8","v0.7.7","v0.7.6","v0.7.5","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7.0","v0.6.7","v0.6.6","v0.6.5","v0.6.4","v0.6.3","v0.6.2","v0.6.1","v0.6.0","v0.5.13","v0.5.12","v0.5.11","v0.5.10","v0.5.9","v0.5.8","v0.5.7","v0.5.6","v0.5.5","v0.5.4","v0.5.3","v0.5.2","v0.5.1","v0.5.0","v0.4.2","v0.4.1","v0.4.0","v0.3.3","v0.3.2","v0.3.1","v0.3.0","v0.2.6","v0.2.5","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46527.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}