{"id":"UBUNTU-CVE-2026-63382","details":"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.","modified":"2026-09-02T19:41:01.970629938Z","published":"2026-08-21T00:00:00Z","related":["USN-8710-1"],"upstream":["CVE-2026-63382"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-63382"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-63382"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8710-1"}],"affected":[{"package":{"name":"libevent","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.21-stable-1ubuntu1.14.04.2+esm1"}]}],"versions":["2.0.21-stable-1","2.0.21-stable-1ubuntu1","2.0.21-stable-1ubuntu1.14.04.1","2.0.21-stable-1ubuntu1.14.04.2"],"ecosystem_specific":{"binaries":[{"binary_name":"libevent-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm1"},{"binary_name":"libevent-core-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm1"},{"binary_name":"libevent-extra-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm1"},{"binary_name":"libevent-openssl-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm1"},{"binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm1","binary_name":"libevent-pthreads-2.0-5"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.21-stable-2ubuntu0.16.04.1+esm1"}]}],"versions":["2.0.21-stable-2","2.0.21-stable-2ubuntu0.16.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libevent-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm1"},{"binary_name":"libevent-core-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm1"},{"binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm1","binary_name":"libevent-extra-2.0-5"},{"binary_name":"libevent-openssl-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm1"},{"binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm1","binary_name":"libevent-pthreads-2.0-5"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.8-stable-4ubuntu0.1~esm1"}]}],"versions":["2.1.8-stable-4","2.1.8-stable-4build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libevent-2.1-6","binary_version":"2.1.8-stable-4ubuntu0.1~esm1"},{"binary_version":"2.1.8-stable-4ubuntu0.1~esm1","binary_name":"libevent-core-2.1-6"},{"binary_version":"2.1.8-stable-4ubuntu0.1~esm1","binary_name":"libevent-extra-2.1-6"},{"binary_name":"libevent-openssl-2.1-6","binary_version":"2.1.8-stable-4ubuntu0.1~esm1"},{"binary_name":"libevent-pthreads-2.1-6","binary_version":"2.1.8-stable-4ubuntu0.1~esm1"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.11-stable-1ubuntu0.1~esm1"}]}],"versions":["2.1.8-stable-4build1","2.1.11-stable-1~exp0","2.1.11-stable-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libevent-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"},{"binary_version":"2.1.11-stable-1ubuntu0.1~esm1","binary_name":"libevent-core-2.1-7"},{"binary_name":"libevent-extra-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"},{"binary_name":"libevent-openssl-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"},{"binary_name":"libevent-pthreads-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.12-stable-1ubuntu0.1"}]}],"versions":["2.1.12-stable-1","2.1.12-stable-1build1","2.1.12-stable-1build2","2.1.12-stable-1build3"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libevent-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_version":"2.1.12-stable-1ubuntu0.1","binary_name":"libevent-core-2.1-7"},{"binary_name":"libevent-extra-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_name":"libevent-openssl-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_version":"2.1.12-stable-1ubuntu0.1","binary_name":"libevent-pthreads-2.1-7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.12-stable-9ubuntu2.1"}]}],"versions":["2.1.12-stable-9","2.1.12-stable-9ubuntu2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libevent-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.1"},{"binary_name":"libevent-core-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.1"},{"binary_name":"libevent-extra-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.1"},{"binary_name":"libevent-openssl-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.1"},{"binary_name":"libevent-pthreads-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}},{"package":{"name":"libevent","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libevent?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.12-stable-10ubuntu0.1"}]}],"versions":["2.1.12-stable-10build1","2.1.12-stable-10build2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"2.1.12-stable-10ubuntu0.1","binary_name":"libevent-2.1-7t64"},{"binary_version":"2.1.12-stable-10ubuntu0.1","binary_name":"libevent-core-2.1-7t64"},{"binary_version":"2.1.12-stable-10ubuntu0.1","binary_name":"libevent-extra-2.1-7t64"},{"binary_name":"libevent-openssl-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.1"},{"binary_name":"libevent-pthreads-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63382.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}