evtchn: Race between FIFO expand and reset

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-62432",
    "assignerOrgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
    "assignerShortName": "XEN",
    "dateUpdated": "2026-07-28T13:34:14.173Z",
    "dateReserved": "2026-07-14T10:28:12.655Z",
    "datePublished": "2026-07-28T12:32:52.043Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "23aa2041-22e1-471f-9209-9b7396fa234f",
        "shortName": "XEN",
        "dateUpdated": "2026-07-28T12:32:52.043Z"
      },
      "datePublic": "2026-07-28T12:00:00.000Z",
      "title": "evtchn: Race between FIFO expand and reset",
      "descriptions": [
        {
          "lang": "en",
          "value": "The EVTCHNOP_expand_array hypercall checks for whether FIFO event\nchannels are enabled, but without holding the correct lock.  It can race\nwith EVTCHNOP_reset, resulting in dereferencing a NULL pointer."
        }
      ],
      "affected": [
        {
          "vendor": "Xen",
          "product": "Xen",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "consult Xen advisory XSA-505",
              "status": "unknown"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://xenbits.xenproject.org/xsa/advisory-505.html"
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "A malicious HVM guest (x86 HVM or PVH, and ARM) can crash Xen leading to\na denial of service.\n\nA malicious x86 PV guest can most likely crash Xen leading to a denial\nof service, but memory corruption or privilege escalation cannot be\nruled out."
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "value": "All Xen versions from 4.5 onwards are vulnerable.  Xen versions 4.4 and\nearlier are not vulnerable."
        }
      ],
      "workarounds": [
        {
          "lang": "en",
          "value": "There are no mitigations."
        }
      ]
    },
    "adp": [
      {
        "providerMetadata": {
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE",
          "dateUpdated": "2026-07-28T13:34:14.173Z"
        },
        "title": "CVE Program Container",
        "references": [
          {
            "url": "http://xenbits.xen.org/xsa/advisory-505.html"
          }
        ]
      }
    ]
  }
}