GHSA-66MV-WQ2C-77C3
Vulnerability from github – Published: 2026-08-28 09:31 – Updated: 2026-09-07 18:31In 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).
{
"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": "HIGH"
},
"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": "2026-09-07T18:31:31Z",
"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/0ce59c4148ecd1520c5592a63bb3c8991ee2d326"
},
{
"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/3f5677d2f817355147337f0453174c7bb0f3b66a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5b4f2bec7bea6c04084d720d731bedee7caf878d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a5edadbae57e2298a56cf7a4e774a027905a331f"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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