{"id":"UBUNTU-CVE-2026-63381","details":"Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf-\u003efirst, outbuf-\u003elast, or outbuf-\u003elast_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.","modified":"2026-09-02T19:41:08.823924032Z","published":"2026-08-21T00:00:00Z","related":["USN-8710-1"],"upstream":["CVE-2026-63381"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-63381"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-63381"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8710-1"}],"affected":[{"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_version":"2.1.8-stable-4ubuntu0.1~esm1","binary_name":"libevent-pthreads-2.1-6"}],"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-2026-63381.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_name":"libevent-core-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"},{"binary_name":"libevent-extra-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm1"},{"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"}],"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-2026-63381.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":{"binaries":[{"binary_name":"libevent-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_name":"libevent-core-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_name":"libevent-extra-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.1"},{"binary_version":"2.1.12-stable-1ubuntu0.1","binary_name":"libevent-openssl-2.1-7"},{"binary_version":"2.1.12-stable-1ubuntu0.1","binary_name":"libevent-pthreads-2.1-7"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63381.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_version":"2.1.12-stable-9ubuntu2.1","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_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-2026-63381.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_name":"libevent-core-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.1"},{"binary_name":"libevent-extra-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.1"},{"binary_name":"libevent-openssl-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.1"},{"binary_version":"2.1.12-stable-10ubuntu0.1","binary_name":"libevent-pthreads-2.1-7t64"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63381.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}