{"id":"CVE-2026-63382","title":"Libevent is an event notification library","summary":"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…","severity":"critical","cvss":9.2,"cvssVector":"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","cwe":["CWE-444"],"vendor":"libevent","product":"libevent","affected":["libevent >= 2.2.0-alpha, < 2.2.2-alpha","libevent < 2.1.13"],"published":"2026-08-20","updated":"2026-09-09","sourceUpdated":"2026-09-09T21:19:49.197","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-63382","references":[{"url":"https://github.com/libevent/libevent/commit/10abb34b8dc3e1184de315dd261ce4b77563cda6","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/commit/5119ceb00557bf007f9065709e852686f3c0bb6e","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/commit/83ba67373032334559b82409db035dd8c3cc1660","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/commit/ac38703b2d312200c4f967f02936af0118d384a0","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j","label":"security-advisories@github.com"},{"url":"https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63382.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-63382"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2520660"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63382"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63382"},{"url":"https://access.redhat.com/errata/RHSA-2026:67909"},{"url":"https://access.redhat.com/errata/RHSA-2026:67908"},{"url":"https://access.redhat.com/errata/RHSA-2026:67910"},{"url":"https://access.redhat.com/errata/RHSA-2026:63388"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"total","timestamp":"2026-08-20T19:33:43.608585Z"},"cvssSource":"cna","ingestedAt":"2026-09-14T14:04:14.885Z","epss":0.00587,"epssPercentile":0.46507,"patched":["enterprise_linux_appstream_v_10","enterprise_linux_appstream_v_8","enterprise_linux_appstream_v_9","enterprise_linux_baseos_v_10","enterprise_linux_baseos_v_8","enterprise_linux_baseos_v_9","hardened_images"],"scores":{"cna":9.2,"vendor":7.7},"slug":"CVE-2026-63382","body":"## Overview\n\nLibevent 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:67909** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67909)\n- **RHSA-2026:67908** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67908)\n- **RHSA-2026:67910** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9) · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:67910)\n- **RHSA-2026:63388** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:63388)\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat OpenShift Container Platform 4 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63382.json)","depth":"abyssal","depthScore":63,"depthScoreParts":{"impact":50.6,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[]}