{"cve":"CVE-2026-63382","nvd":{"published":"2026-08-20T18:16:35.700","modified":"2026-10-26T10:10:00.140","status":"Awaiting Analysis","description":"Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, the libevent evhttp parser in http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding values, and bare line feeds in chunked framing. evhttp_find_header can select only the first header, evhttp_check_transfer_encoding_ was absent so the previous whole-string comparison fails to recognize valid lists ending in chunked, and evhttp_handle_chunked_read uses EVBUFFER_EOL_CRLF rather than EVBUFFER_EOL_CRLF_STRICT, accepting bare LF chunk terminators. When libevent is deployed behind a proxy that frames the same request differently, an unauthenticated remote attacker can desynchronize request boundaries and smuggle a second request, potentially bypassing access controls or poisoning caches. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N","score":9.2},"cvss_v3":null,"cwes":["CWE-444"],"references":["https://github.com/libevent/libevent/commit/10abb34b8dc3e1184de315dd261ce4b77563cda6","https://github.com/libevent/libevent/commit/5119ceb00557bf007f9065709e852686f3c0bb6e","https://github.com/libevent/libevent/commit/83ba67373032334559b82409db035dd8c3cc1660","https://github.com/libevent/libevent/commit/ac38703b2d312200c4f967f02936af0118d384a0","https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"],"products":[],"source":"nvd","synced_at":"2026-10-26T10:28:23.151169805+00:00"},"epss":{"cve":"CVE-2026-63382","score":0.00784,"percentile":0.55763,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}