CVE-2026-63387

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{"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."}, {"lang": "es", "value": "Libevent es una biblioteca de notificaci\u00f3n de eventos. Antes de 2.1.13 y 2.2.2-alpha, libevent tiene un desbordamiento de b\u00fafer de pila por un byte en evdns.c cuando dnsname_to_labels formatea un registro DNS que contiene un nombre al final del b\u00fafer de pila de 64 KB asignado por evdns_server_request_format_response. La verificaci\u00f3n de la etiqueta final permite que j m\u00e1s label_len m\u00e1s uno sea igual a buf_len, despu\u00e9s de lo cual el byte nulo de terminaci\u00f3n se escribe en buf[buf_len]. Una respuesta de servidor DNS manipulada que contiene datos PTR, CNAME, MX, NS o SOA puede desencadenar la escritura fuera de l\u00edmites de un byte y bloquear o corromper el proceso. Este problema est\u00e1 solucionado en las versiones 2.1.13 y 2.2.2-alpha."}], "id": "CVE-2026-63387", "lastModified": "2026-10-26T10:10:00.140", "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"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-63387", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-25T15:11:49.042805Z", "version": "2.0.3"}}]}, "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"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-121"}, {"lang": "en", "value": "CWE-193"}, {"lang": "en", "value": "CWE-787"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"bugzilla": {"description": "libevent: Libevent: Off-by-one stack buffer overflow leading to denial of service or data corruption", "id": "2520655", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2520655"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.6", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H", "status": "draft"}, "cwe": "CWE-787", "details": ["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.", "A flaw was found in Libevent, an event notification library. An off-by-one stack buffer overflow exists in the `dnsname_to_labels` function when processing a name-bearing DNS record. A remote attacker could send a specially crafted DNS server response, which may lead to a crash or corruption of the process, resulting in a denial of service or potential information disclosure and integrity impact."], "name": "CVE-2026-63387", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Affected", "package_name": "libevent2", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "libevent", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-08-20T17:53:41Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-63387\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63387\nhttps://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\nhttps://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\nhttps://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"], "threat_severity": "Important"}

{"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"]}