CVE-2026-63495

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{"affected": [{"affectedData": [{"product": "libevent", "vendor": "libevent", "versions": [{"status": "affected", "version": ">= 2.2.0-alpha-dev, < 2.2.2-alpha"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha."}, {"lang": "es", "value": "Libevent es una biblioteca de notificaci\u00f3n de eventos. Desde 2.2.0-alpha-dev hasta 2.2.2-alpha, el servidor WebSocket de libevent en ws.c acumula tramas fragmentadas en evws -> incomplete_frames sin aplicar un l\u00edmite de tama\u00f1o total de mensaje. Un cliente remoto no autenticado puede enviar repetidamente tramas WebSocket fragmentadas por debajo de WS_MAX_RECV_FRAME_SZ con FIN=0, haciendo que el evbuffer crezca sin l\u00edmite hasta que el proceso o el host agote la memoria. Este problema est\u00e1 solucionado en la versi\u00f3n 2.2.2-alpha."}], "id": "CVE-2026-63495", "lastModified": "2026-10-26T10:10:00.140", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-63495", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-20T19:16:58.376889Z", "version": "2.0.3"}}]}, "published": "2026-08-20T18:16:37.040", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b"}, {"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-qx89-wf2v-vgmx"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-770"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{"affected_release": [{"advisory": "RHSA-2026:41176", "cpe": "cpe:/a:redhat:hummingbird:1", "package": "libevent-main-2.1.12-19.hum1", "product_name": "Red Hat Hardened Images", "release_date": "2026-07-17T00:00:00Z"}], "bugzilla": {"description": "libevent: Libevent: Remote denial of service via unbounded memory accumulation in WebSocket server", "id": "2520659", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2520659"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "verified"}, "cwe": "CWE-770", "details": ["Libevent is an event notification library. From 2.2.0-alpha-dev until 2.2.2-alpha, the libevent WebSocket server in ws.c accumulates fragmented frames in evws->incomplete_frames without enforcing a total message-size limit. An unauthenticated remote client can repeatedly send fragmented WebSocket frames below WS_MAX_RECV_FRAME_SZ with FIN=0, causing the evbuffer to grow without bound until the process or host exhausts memory. This issue is fixed in version 2.2.2-alpha.", "A flaw was found in Libevent. An unauthenticated remote client can exploit this vulnerability by repeatedly sending fragmented WebSocket frames to the Libevent WebSocket server. Due to a lack of a total message-size limit, these fragmented frames accumulate in memory without bound, leading to memory exhaustion and a denial of service (DoS) for the process or host."], "name": "CVE-2026-63495", "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: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": "2026-08-20T17:49:16Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-63495\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63495\nhttps://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b\nhttps://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\nhttps://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx"], "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.2.0-alpha-dev,2.2.2-alpha)"}}], "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": "2026-08-21T02:15:04.424719+00:00", "updated": "2026-08-21T13:01:16.396518+00:00", "vendors": ["libevent_project", "libevent_project$PRODUCT$libevent"]}