{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/vhost/vhost.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e115471008111f894c6528d9ab2ce7d0ce306f35",
              "status": "affected",
              "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
              "versionType": "git"
            },
            {
              "lessThan": "7f229d27bf27c7e589eca690d8612763a7a4801f",
              "status": "affected",
              "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
              "versionType": "git"
            },
            {
              "lessThan": "a9326b652bc7acd748d7a1143573845c7924d847",
              "status": "affected",
              "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
              "versionType": "git"
            },
            {
              "lessThan": "09861858a68342f851f71c669ac0f69865c32151",
              "status": "affected",
              "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/vhost/vhost.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvhost: fix vhost_get_avail_idx for a non empty ring\n\nvhost_get_avail_idx is supposed to report whether it has updated\nvq-\u003eavail_idx. Instead, it returns whether all entries have been\nconsumed, which is usually the same. But not always - in\ndrivers/vhost/net.c and when mergeable buffers have been enabled, the\ndriver checks whether the combined entries are big enough to store an\nincoming packet. If not, the driver re-enables notifications with\navailable entries still in the ring. The incorrect return value from\nvhost_get_avail_idx propagates through vhost_enable_notify and causes\nthe host to livelock if the guest is not making progress, as vhost will\nimmediately disable notifications and retry using the available entries.\n\nThis goes back to commit d3bb267bbdcb (\"vhost: cache avail index in\nvhost_enable_notify()\") which changed vhost_enable_notify() to compare\nthe freshly read avail index against vq-\u003elast_avail_idx instead of the\npreviously cached vq-\u003eavail_idx. Commit 7ad472397667 (\"vhost: move\nsmp_rmb() into vhost_get_avail_idx()\") then carried over the same\ncomparison when refactoring vhost_enable_notify() to call the unified\nvhost_get_avail_idx().\n\nThe obvious fix is to make vhost_get_avail_idx do what the comment\nsays it does and report whether new entries have been added."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - Exploitation requires a malicious VM guest driving the virtio/vhost-net RX virtqueue on a KVM host; inbound packets cross the adjacent virtual-network boundary into host vhost-net processing, matching kernel CNA precedent for guest-to-host vhost-net bugs.\nAC:L - A guest can deterministically enable mergeable RX buffers, post undersized descriptors, stop refilling, and sustain inbound traffic so handle_rx() repeatedly hits the faulty vhost_enable_notify()/vhost_get_avail_idx() loop without races or rare configs.\nPR:N - A cloud VM tenant or any attacker with code execution inside a vhost-net guest needs no host root, capabilities, or /dev/vhost-net access\u2014only control of the guest virtio RX ring and normal VM networking, which QEMU/KVM provides by default.\nUI:N - No host administrator or victim user action is required beyond standard VM operation; the guest attacker directly manipulates virtio descriptors and can generate or receive the RX traffic that triggers host-side vhost processing.\nS:C - The livelock executes in host kernel vhost worker context while processing guest-controlled virtio ring state, crossing the VM/host isolation boundary and degrading availability for the hypervisor and co-hosted workloads beyond the guest\u0027s own scope.\nC:N - This is a pure logic error in available-index comparison causing a notification retry loop; there is no memory corruption, out-of-bounds access, use-after-free, or other primitive that could disclose kernel memory.\nI:N - No kernel memory is corrupted or written beyond the virtio notification state machine; the bug cannot be leveraged for arbitrary write, control-flow hijacking, or code execution on the host.\nA:H - The faulty vhost_enable_notify() loop causes host CPU livelock when the guest stops making progress, pinning a vhost worker at 100% and denying service to the host and other VMs until the offending guest is stopped or killed."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:46:17.196Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e115471008111f894c6528d9ab2ce7d0ce306f35"
        },
        {
          "url": "https://git.kernel.org/stable/c/7f229d27bf27c7e589eca690d8612763a7a4801f"
        },
        {
          "url": "https://git.kernel.org/stable/c/a9326b652bc7acd748d7a1143573845c7924d847"
        },
        {
          "url": "https://git.kernel.org/stable/c/09861858a68342f851f71c669ac0f69865c32151"
        }
      ],
      "title": "vhost: fix vhost_get_avail_idx for a non empty ring",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74356",
    "datePublished": "2026-08-15T05:58:41.445Z",
    "dateReserved": "2026-08-15T05:44:03.887Z",
    "dateUpdated": "2026-08-17T05:46:17.196Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}