Vulnerability-Lookup

GHSA-4CVR-85R6-XWMJ

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)

Hygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and share the same erratum #1235: hardware may read a stale IsRunning=1 bit during ICR write emulation and silently fail to generate an AVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU.

The absence of the VM-Exit causes KVM to miss the required wakeup of blocking target vCPUs, leading to hung vCPUs and unbounded delays in guest execution.

Extend the existing AMD Family 17h erratum #1235 workaround to also cover Hygon Family 18h. With IPI virtualization disabled, KVM never sets IsRunning=1 in the Physical ID table, so every non-self IPI generates a VM-Exit and is correctly emulated.

Severity

7.1 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64172"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:59Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)\n\nHygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and\nshare the same erratum #1235: hardware may read a stale IsRunning=1 bit\nduring ICR write emulation and silently fail to generate an\nAVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU.\n\nThe absence of the VM-Exit causes KVM to miss the required wakeup of\nblocking target vCPUs, leading to hung vCPUs and unbounded delays in\nguest execution.\n\nExtend the existing AMD Family 17h erratum #1235 workaround to also cover\nHygon Family 18h.  With IPI virtualization disabled, KVM never sets\nIsRunning=1 in the Physical ID table, so every non-self IPI generates a\nVM-Exit and is correctly emulated.",
  "id": "GHSA-4cvr-85r6-xwmj",
  "modified": "2026-07-20T15:32:02Z",
  "published": "2026-07-19T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64172"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/94ade38f317ea086a181db0e6b69c574b3b70a5e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9560e6fee887a9594a89fa265b5b9c79b1591803"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a12fa5213cfc391e0eed63902d3be98f0913765"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-64172 (GCVE-0-2026-64172)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-20 13:43

Title

KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235) Hygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and share the same erratum #1235: hardware may read a stale IsRunning=1 bit during ICR write emulation and silently fail to generate an AVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU. The absence of the VM-Exit causes KVM to miss the required wakeup of blocking target vCPUs, leading to hung vCPUs and unbounded delays in guest execution. Extend the existing AMD Family 17h erratum #1235 workaround to also cover Hygon Family 18h. With IPI virtualization disabled, KVM never sets IsRunning=1 in the Physical ID table, so every non-self IPI generates a VM-Exit and is correctly emulated.

Severity

7.1 (High)


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

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/94ade38f317ea086a…
https://git.kernel.org/stable/c/9560e6fee887a9594…
https://git.kernel.org/stable/c/9a12fa5213cfc391e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 8de4a1c8164e5b2e40d1df764840a31de983f40b , < 94ade38f317ea086a181db0e6b69c574b3b70a5e (git) Affected: 8de4a1c8164e5b2e40d1df764840a31de983f40b , < 9560e6fee887a9594a89fa265b5b9c79b1591803 (git) Affected: 8de4a1c8164e5b2e40d1df764840a31de983f40b , < 9a12fa5213cfc391e0eed63902d3be98f0913765 (git)
Linux	Linux	Affected: 6.17 Unaffected: 0 , < 6.17 (semver) Unaffected: 6.18.34 , ≤ 6.18.* (semver) Unaffected: 7.0.11 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/kvm/svm/avic.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "94ade38f317ea086a181db0e6b69c574b3b70a5e",
              "status": "affected",
              "version": "8de4a1c8164e5b2e40d1df764840a31de983f40b",
              "versionType": "git"
            },
            {
              "lessThan": "9560e6fee887a9594a89fa265b5b9c79b1591803",
              "status": "affected",
              "version": "8de4a1c8164e5b2e40d1df764840a31de983f40b",
              "versionType": "git"
            },
            {
              "lessThan": "9a12fa5213cfc391e0eed63902d3be98f0913765",
              "status": "affected",
              "version": "8de4a1c8164e5b2e40d1df764840a31de983f40b",
              "versionType": "git"
            }
          ]
        },
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.17"
            },
            {
              "lessThan": "6.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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                }
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      "descriptions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)\n\nHygon Family 18h CPUs are derived from AMD Family 17h (Zen1) silicon and\nshare the same erratum #1235: hardware may read a stale IsRunning=1 bit\nduring ICR write emulation and silently fail to generate an\nAVIC_IPI_FAILURE_TARGET_NOT_RUNNING VM-Exit on the sending vCPU.\n\nThe absence of the VM-Exit causes KVM to miss the required wakeup of\nblocking target vCPUs, leading to hung vCPUs and unbounded delays in\nguest execution.\n\nExtend the existing AMD Family 17h erratum #1235 workaround to also cover\nHygon Family 18h.  With IPI virtualization disabled, KVM never sets\nIsRunning=1 in the Physical ID table, so every non-self IPI generates a\nVM-Exit and is correctly emulated."
        }
      ],
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        {
          "url": "https://git.kernel.org/stable/c/9a12fa5213cfc391e0eed63902d3be98f0913765"
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      ],
      "title": "KVM: SVM: Disable AVIC IPI virtualization on Hygon Family 18h (erratum #1235)",
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    "datePublished": "2026-07-19T15:40:57.153Z",
    "dateReserved": "2026-07-19T07:54:57.039Z",
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}

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.

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GHSA-4CVR-85R6-XWMJ

CVE-2026-64172 (GCVE-0-2026-64172)

Tags

Sightings

Nomenclature