CVE-2026-63495

{
  "id": "CVE-2026-63495",
  "sourceIdentifier": "[email protected]",
  "published": "2026-08-20T18:16:37.040",
  "lastModified": "2026-10-26T10:10:00.140",
  "vulnStatus": "Awaiting Analysis",
  "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 notificación 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 límite de tamaño 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 límite hasta que el proceso o el host agote la memoria. Este problema está solucionado en la versión 2.2.2-alpha."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "libevent",
          "product": "libevent",
          "versions": [
            {
              "version": ">= 2.2.0-alpha-dev, < 2.2.2-alpha",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-20T19:16:58.376889Z",
          "id": "CVE-2026-63495",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-770"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/libevent/libevent/commit/291c4d1cd75695e898030ebd5c4ddf26c094077b",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/libevent/libevent/security/advisories/GHSA-qx89-wf2v-vgmx",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ]
}