{"id":"USN-8840-1","summary":"libevent vulnerabilities","details":"Michał Majchrowicz and Marcin Wyczechowski discovered that libevent\nincorrectly handled certain DNS responses. A remote attacker could possibly\nuse this issue to cause a denial of service or execute arbitrary code.\n(CVE-2026-63387)\n\nIt was discovered that libevent incorrectly handled certain connections. A\nlocal attacker could possibly use this issue to cause a denial of service\nor execute arbitrary code. This issue only affected Ubuntu 18.04 LTS,\nUbuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS.\n(CVE-2026-63388)","modified":"2026-09-29T23:56:46.660677500Z","published":"2026-09-28T20:05:19Z","related":["UBUNTU-CVE-2026-63387","UBUNTU-CVE-2026-63388"],"upstream":["CVE-2026-63387","CVE-2026-63388","UBUNTU-CVE-2026-63387","UBUNTU-CVE-2026-63388"],"references":[{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8840-1"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-63387"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-63388"}],"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+esm2"}]}],"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","2.0.21-stable-1ubuntu1.14.04.2+esm1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","binaries":[{"binary_name":"libevent-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm2"},{"binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm2","binary_name":"libevent-core-2.0-5"},{"binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm2","binary_name":"libevent-extra-2.0-5"},{"binary_name":"libevent-openssl-2.0-5","binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm2"},{"binary_version":"2.0.21-stable-1ubuntu1.14.04.2+esm2","binary_name":"libevent-pthreads-2.0-5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json","cves_map":{"ecosystem":"Ubuntu:Pro:14.04:LTS","cves":[]}}},{"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+esm2"}]}],"versions":["2.0.21-stable-2","2.0.21-stable-2ubuntu0.16.04.1","2.0.21-stable-2ubuntu0.16.04.1+esm1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","binaries":[{"binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm2","binary_name":"libevent-2.0-5"},{"binary_name":"libevent-core-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm2"},{"binary_name":"libevent-extra-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm2"},{"binary_name":"libevent-openssl-2.0-5","binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm2"},{"binary_version":"2.0.21-stable-2ubuntu0.16.04.1+esm2","binary_name":"libevent-pthreads-2.0-5"}]},"database_specific":{"cves_map":{"ecosystem":"Ubuntu:Pro:16.04:LTS","cves":[]},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.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~esm2"}]}],"versions":["2.1.8-stable-4","2.1.8-stable-4build1","2.1.8-stable-4ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"2.1.8-stable-4ubuntu0.1~esm2","binary_name":"libevent-2.1-6"},{"binary_name":"libevent-core-2.1-6","binary_version":"2.1.8-stable-4ubuntu0.1~esm2"},{"binary_version":"2.1.8-stable-4ubuntu0.1~esm2","binary_name":"libevent-extra-2.1-6"},{"binary_version":"2.1.8-stable-4ubuntu0.1~esm2","binary_name":"libevent-openssl-2.1-6"},{"binary_name":"libevent-pthreads-2.1-6","binary_version":"2.1.8-stable-4ubuntu0.1~esm2"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json","cves_map":{"ecosystem":"Ubuntu:Pro:18.04:LTS","cves":[{"id":"CVE-2026-63388","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}]}}},{"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~esm2"}]}],"versions":["2.1.8-stable-4build1","2.1.11-stable-1~exp0","2.1.11-stable-1","2.1.11-stable-1ubuntu0.1~esm1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"libevent-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm2"},{"binary_name":"libevent-core-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm2"},{"binary_name":"libevent-extra-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm2"},{"binary_name":"libevent-openssl-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm2"},{"binary_name":"libevent-pthreads-2.1-7","binary_version":"2.1.11-stable-1ubuntu0.1~esm2"}]},"database_specific":{"cves_map":{"ecosystem":"Ubuntu:Pro:20.04:LTS","cves":[{"id":"CVE-2026-63388","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}]},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.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-1ubuntu0.2"}]}],"versions":["2.1.12-stable-1","2.1.12-stable-1build1","2.1.12-stable-1build2","2.1.12-stable-1build3","2.1.12-stable-1ubuntu0.1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libevent-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.2"},{"binary_name":"libevent-core-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.2"},{"binary_version":"2.1.12-stable-1ubuntu0.2","binary_name":"libevent-extra-2.1-7"},{"binary_name":"libevent-openssl-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.2"},{"binary_name":"libevent-pthreads-2.1-7","binary_version":"2.1.12-stable-1ubuntu0.2"}]},"database_specific":{"cves_map":{"ecosystem":"Ubuntu:22.04:LTS","cves":[{"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-63388"}]},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.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-9ubuntu2.2"}]}],"versions":["2.1.12-stable-9","2.1.12-stable-9ubuntu2","2.1.12-stable-9ubuntu2.1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libevent-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.2"},{"binary_version":"2.1.12-stable-9ubuntu2.2","binary_name":"libevent-core-2.1-7t64"},{"binary_version":"2.1.12-stable-9ubuntu2.2","binary_name":"libevent-extra-2.1-7t64"},{"binary_name":"libevent-openssl-2.1-7t64","binary_version":"2.1.12-stable-9ubuntu2.2"},{"binary_version":"2.1.12-stable-9ubuntu2.2","binary_name":"libevent-pthreads-2.1-7t64"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json","cves_map":{"cves":[{"severity":[{"score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}],"id":"CVE-2026-63388"}],"ecosystem":"Ubuntu:24.04:LTS"}}},{"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-10ubuntu0.2"}]}],"versions":["2.1.12-stable-10build1","2.1.12-stable-10build2","2.1.12-stable-10ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_version":"2.1.12-stable-10ubuntu0.2","binary_name":"libevent-2.1-7t64"},{"binary_version":"2.1.12-stable-10ubuntu0.2","binary_name":"libevent-core-2.1-7t64"},{"binary_name":"libevent-extra-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.2"},{"binary_version":"2.1.12-stable-10ubuntu0.2","binary_name":"libevent-openssl-2.1-7t64"},{"binary_name":"libevent-pthreads-2.1-7t64","binary_version":"2.1.12-stable-10ubuntu0.2"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8840-1.json","cves_map":{"ecosystem":"Ubuntu:26.04:LTS","cves":[{"id":"CVE-2026-63387","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H"},{"type":"Ubuntu","score":"medium"}]},{"id":"CVE-2026-63388","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}]}}}],"schema_version":"1.9.0"}