{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63387", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-07-16T17:39:30.171Z", "datePublished": "2026-08-20T17:53:41.863Z", "dateUpdated": "2026-08-20T17:53:41.863Z"}, "containers": {"cna": {"title": "Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response", "problemTypes": [{"descriptions": [{"cweId": "CWE-121", "lang": "en", "description": "CWE-121: Stack-based Buffer Overflow", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-193", "lang": "en", "description": "CWE-193: Off-by-one Error", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-787", "lang": "en", "description": "CWE-787: Out-of-bounds Write", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"}, {"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-2.1.13-stable"}, {"name": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha", "tags": ["x_refsource_MISC"], "url": "https://github.com/libevent/libevent/releases/tag/release-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"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-20T17:53:41.863Z"}, "descriptions": [{"lang": "en", "value": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha."}], "source": {"advisory": "GHSA-58rx-7448-jw47", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "libevent", "vendor": "libevent", "versions": [{"status": "affected", "version": ">= 2.2.0-alpha, < 2.2.2-alpha"}, {"status": "affected", "version": "< 2.1.13"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha."}], "id": "CVE-2026-63387", "lastModified": "2026-08-20T18:16:36.723", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.0, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 4.7, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-20T18:16:36.723", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"}, {"source": "security-advisories@github.com", "url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"}, {"source": "security-advisories@github.com", "url": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}, {"lang": "en", "value": "CWE-193"}, {"lang": "en", "value": "CWE-787"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.2.0-alpha,2.2.2-alpha)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,2.1.13)"}}], "enrichment": {"confidence": 81.0, "confidence_source": "matching", "scores": [{"score": 81.0, "source": "matching"}]}, "original": {"product": "libevent", "source": "cna", "vendor": "libevent"}, "product": "libevent", "vendor": "libevent_project"}], "created": "2026-08-21T02:00:05.423333+00:00", "updated": "2026-08-21T13:01:04.716565+00:00", "vendors": ["libevent_project", "libevent_project$PRODUCT$libevent"]}