{"id":"CVE-2026-63381","state":"PUBLISHED","title":"Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`","description":"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->first, outbuf->last, or outbuf->last_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.","publishedAt":"2026-08-20T17:50:09.322Z","updatedAt":"2026-08-21T21:46:33.792Z","severity":{"score":5.8,"label":"Medium","version":"4.0","vector":"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","source":"GitHub_M"},"assigner":"GitHub_M","products":["libevent libevent"],"affected":[{"vendor":"libevent","product":"libevent","versions":[{"version":">= 2.2.0-alpha, < 2.2.2-alpha","status":"affected"},{"version":"< 2.1.13","status":"affected"}]}],"references":["https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-cg4r-88c8","https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c","https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9","https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable","https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"],"weaknesses":["CWE-908"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63381.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63381","state":"PUBLISHED","datePublished":"2026-08-20T17:50:09.322Z","dateUpdated":"2026-08-21T21:46:33.792Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-16T17:39:30.171Z"},"containers":{"cna":{"title":"Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`","descriptions":[{"lang":"en","value":"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->first, outbuf->last, or outbuf->last_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."}],"affected":[{"vendor":"libevent","product":"libevent","versions":[{"version":">= 2.2.0-alpha, < 2.2.2-alpha","status":"affected"},{"version":"< 2.1.13","status":"affected"}]}],"references":[{"url":"https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-cg4r-88c8","name":"https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-cg4r-88c8","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c","name":"https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c","tags":["x_refsource_MISC"]},{"url":"https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9","name":"https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9","tags":["x_refsource_MISC"]},{"url":"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable","name":"https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable","tags":["x_refsource_MISC"]},{"url":"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha","name":"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":5.8,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-908","lang":"en","description":"CWE-908: Use of Uninitialized Resource","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-20T17:50:09.322Z"},"source":{"advisory":"GHSA-c2pj-cg4r-88c8","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T20:58:46.599802Z","id":"CVE-2026-63381","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T21:46:33.792Z"}}]}}}