CVE Catalog

CVE-2026-80724

HighCVSS 8.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.12%

2th percentile - higher than 2% of all known CVEs

Summary

In the Linux kernel, a vulnerability in ptp: vmclock was fixed that allowed read-only mappings to become writable. The vmclock_miscdev_mmap() function rejected writable mappings of the shared vmclock ABI page with -EROFS, but left VM_MAYWRITE set. Userspace could map the page read-only and then upgrade it to writable with mprotect(), allowing the guest to corrupt host-written timekeeping data (sequence counter, UTC time, TSC offset) that the vmclock ABI defines as read-only. The fix clears VM_MAYWRITE on the read-only path so the mapping cannot be upgraded.

Risk Assessment

A guest user can gain writable access to timekeeping data that should be read-only, potentially leading to data integrity violation and further system attacks.

Recommendation

Apply the Linux kernel update containing this fix. If not possible, restrict access to vmclock devices for untrusted users.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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).

Vulnerability data from NVD (NIST) · CISA KEV · EPSS