Vulnerability-Lookup

GHSA-66MV-WQ2C-77C3

Vulnerability from github – Published: 2026-08-28 09:31 – Updated: 2026-08-28 09:31

Details

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

ptp: vmclock: prevent read-only mappings from becoming writable

vmclock_miscdev_mmap() rejects writable mappings of the shared vmclock ABI page with -EROFS, but leaves VM_MAYWRITE set. Userspace can map the page read-only and then upgrade it to writable with mprotect(), after which the guest can corrupt the host-written timekeeping data (sequence counter, UTC time, TSC offset) that the vmclock ABI defines as read-only.

Clear VM_MAYWRITE on the read-only path so the mapping cannot be upgraded, as i915 does for its read-only objects and as fixed in drm/vc4 (CVE-2026-68445) and drm/panthor (CVE-2024-53071).

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80724"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-28T08:16:58Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nptp: vmclock: prevent read-only mappings from becoming writable\n\nvmclock_miscdev_mmap() rejects writable mappings of the shared vmclock\nABI page with -EROFS, but leaves VM_MAYWRITE set.  Userspace can map the\npage read-only and then upgrade it to writable with mprotect(), after\nwhich the guest can corrupt the host-written timekeeping data (sequence\ncounter, UTC time, TSC offset) that the vmclock ABI defines as read-only.\n\nClear VM_MAYWRITE on the read-only path so the mapping cannot be\nupgraded, as i915 does for its read-only objects and as fixed in drm/vc4\n(CVE-2026-68445) and drm/panthor (CVE-2024-53071).",
  "id": "GHSA-66mv-wq2c-77c3",
  "modified": "2026-08-28T09:31:50Z",
  "published": "2026-08-28T09:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80724"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2496e141827102d6af512950057d402a2cfb2bfc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e596e7814ba38cdc129991058b6c254ed37cb11"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5b4f2bec7bea6c04084d720d731bedee7caf878d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-80724 (GCVE-0-2026-80724)

Vulnerability from cvelistv5 – Published: 2026-08-28 07:03 – Updated: 2026-08-28 07:03

Title

ptp: vmclock: prevent read-only mappings from becoming writable

Summary

In the Linux kernel, the following vulnerability has been resolved: ptp: vmclock: prevent read-only mappings from becoming writable vmclock_miscdev_mmap() rejects writable mappings of the shared vmclock ABI page with -EROFS, but leaves VM_MAYWRITE set. Userspace can map the page read-only and then upgrade it to writable with mprotect(), after which the guest can corrupt the host-written timekeeping data (sequence counter, UTC time, TSC offset) that the vmclock ABI defines as read-only. Clear VM_MAYWRITE on the read-only path so the mapping cannot be upgraded, as i915 does for its read-only objects and as fixed in drm/vc4 (CVE-2026-68445) and drm/panthor (CVE-2024-53071).

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/5b4f2bec7bea6c040…
https://git.kernel.org/stable/c/2496e141827102d6a…
https://git.kernel.org/stable/c/2e596e7814ba38cdc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 20503272422693d793b84f88bf23fe4e955d3a33 , < 5b4f2bec7bea6c04084d720d731bedee7caf878d (git) Affected: 20503272422693d793b84f88bf23fe4e955d3a33 , < 2496e141827102d6af512950057d402a2cfb2bfc (git) Affected: 20503272422693d793b84f88bf23fe4e955d3a33 , < 2e596e7814ba38cdc129991058b6c254ed37cb11 (git)
Linux	Linux	Affected: 6.13 Unaffected: 0 , < 6.13 (semver) Unaffected: 6.18.47 , ≤ 6.18.* (semver) Unaffected: 7.1.11 , ≤ 7.1.* (semver) Unaffected: 7.2.1 , ≤ 7.2.* (semver)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/ptp/ptp_vmclock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5b4f2bec7bea6c04084d720d731bedee7caf878d",
              "status": "affected",
              "version": "20503272422693d793b84f88bf23fe4e955d3a33",
              "versionType": "git"
            },
            {
              "lessThan": "2496e141827102d6af512950057d402a2cfb2bfc",
              "status": "affected",
              "version": "20503272422693d793b84f88bf23fe4e955d3a33",
              "versionType": "git"
            },
            {
              "lessThan": "2e596e7814ba38cdc129991058b6c254ed37cb11",
              "status": "affected",
              "version": "20503272422693d793b84f88bf23fe4e955d3a33",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/ptp/ptp_vmclock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.47",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.1",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.47",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.11",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.1",
                  "versionStartIncluding": "6.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nptp: vmclock: prevent read-only mappings from becoming writable\n\nvmclock_miscdev_mmap() rejects writable mappings of the shared vmclock\nABI page with -EROFS, but leaves VM_MAYWRITE set.  Userspace can map the\npage read-only and then upgrade it to writable with mprotect(), after\nwhich the guest can corrupt the host-written timekeeping data (sequence\ncounter, UTC time, TSC offset) that the vmclock ABI defines as read-only.\n\nClear VM_MAYWRITE on the read-only path so the mapping cannot be\nupgraded, as i915 does for its read-only objects and as fixed in drm/vc4\n(CVE-2026-68445) and drm/panthor (CVE-2024-53071)."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-28T07:03:08.410Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/5b4f2bec7bea6c04084d720d731bedee7caf878d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2496e141827102d6af512950057d402a2cfb2bfc"
        },
        {
          "url": "https://git.kernel.org/stable/c/2e596e7814ba38cdc129991058b6c254ed37cb11"
        }
      ],
      "title": "ptp: vmclock: prevent read-only mappings from becoming writable",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80724",
    "datePublished": "2026-08-28T07:03:08.410Z",
    "dateReserved": "2026-08-26T14:34:25.788Z",
    "dateUpdated": "2026-08-28T07:03:08.410Z",
    "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

GHSA-66MV-WQ2C-77C3

CVE-2026-80724 (GCVE-0-2026-80724)

Tags

Sightings

Nomenclature