Vulnerability-Lookup

FKIE_CVE-2026-74356

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:19

Severity

7.4 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: vhost: fix vhost_get_avail_idx for a non empty ring vhost_get_avail_idx is supposed to report whether it has updated vq->avail_idx. Instead, it returns whether all entries have been consumed, which is usually the same. But not always - in drivers/vhost/net.c and when mergeable buffers have been enabled, the driver checks whether the combined entries are big enough to store an incoming packet. If not, the driver re-enables notifications with available entries still in the ring. The incorrect return value from vhost_get_avail_idx propagates through vhost_enable_notify and causes the host to livelock if the guest is not making progress, as vhost will immediately disable notifications and retry using the available entries. This goes back to commit d3bb267bbdcb ("vhost: cache avail index in vhost_enable_notify()") which changed vhost_enable_notify() to compare the freshly read avail index against vq->last_avail_idx instead of the previously cached vq->avail_idx. Commit 7ad472397667 ("vhost: move smp_rmb() into vhost_get_avail_idx()") then carried over the same comparison when refactoring vhost_enable_notify() to call the unified vhost_get_avail_idx(). The obvious fix is to make vhost_get_avail_idx do what the comment says it does and report whether new entries have been added.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/09861858a68342f851f71c669ac0f69865c32151
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7f229d27bf27c7e589eca690d8612763a7a4801f
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a9326b652bc7acd748d7a1143573845c7924d847
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e115471008111f894c6528d9ab2ce7d0ce306f35

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "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"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-74356",
  "lastModified": "2026-08-17T06:19:30.287",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T06:22:37.007",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/09861858a68342f851f71c669ac0f69865c32151"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7f229d27bf27c7e589eca690d8612763a7a4801f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a9326b652bc7acd748d7a1143573845c7924d847"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e115471008111f894c6528d9ab2ce7d0ce306f35"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-74356 (GCVE-0-2026-74356)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:58 – Updated: 2026-08-17 05:46

Title

vhost: fix vhost_get_avail_idx for a non empty ring

Summary

Severity

7.4 (High)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/e115471008111f894…
https://git.kernel.org/stable/c/7f229d27bf27c7e58…
https://git.kernel.org/stable/c/a9326b652bc7acd74…
https://git.kernel.org/stable/c/09861858a68342f85…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d3bb267bbdcba199568f1325743d9d501dea0560 , < e115471008111f894c6528d9ab2ce7d0ce306f35 (git) Affected: d3bb267bbdcba199568f1325743d9d501dea0560 , < 7f229d27bf27c7e589eca690d8612763a7a4801f (git) Affected: d3bb267bbdcba199568f1325743d9d501dea0560 , < a9326b652bc7acd748d7a1143573845c7924d847 (git) Affected: d3bb267bbdcba199568f1325743d9d501dea0560 , < 09861858a68342f851f71c669ac0f69865c32151 (git)
Linux	Linux	Affected: 5.18 Unaffected: 0 , < 5.18 (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

FKIE_CVE-2026-74356

CVE-2026-74356 (GCVE-0-2026-74356)

Tags

Sightings

Nomenclature