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vhost: fix vhost_get_avail_idx for a non empty ring

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-74356

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74356

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
        "lessThan": "0fe5ca2d56f0122988016e415a074c95925504b7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
        "lessThan": "e115471008111f894c6528d9ab2ce7d0ce306f35",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
        "lessThan": "7f229d27bf27c7e589eca690d8612763a7a4801f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
        "lessThan": "a9326b652bc7acd748d7a1143573845c7924d847",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d3bb267bbdcba199568f1325743d9d501dea0560",
        "lessThan": "09861858a68342f851f71c669ac0f69865c32151",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/vhost/vhost.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.18"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.18",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.97",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.40",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/vhost/vhost.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74356

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#46550 · Revision 1
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Publisher date
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