Linux vulnerability

What happened

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).

Affected versions

Linux: 20503272422693d793b84f88bf23fe4e955d3a33 through before 5b4f2bec7bea6c04084d720d731bedee7caf878d (git); 20503272422693d793b84f88bf23fe4e955d3a33 through before 3f5677d2f817355147337f0453174c7bb0f3b66a (git); 20503272422693d793b84f88bf23fe4e955d3a33 through before 2496e141827102d6af512950057d402a2cfb2bfc (git); 20503272422693d793b84f88bf23fe4e955d3a33 through before 2e596e7814ba38cdc129991058b6c254ed37cb11 (git); 20503272422693d793b84f88bf23fe4e955d3a33 through before 0ce59c4148ecd1520c5592a63bb3c8991ee2d326 (git); 20503272422693d793b84f88bf23fe4e955d3a33 through before a5edadbae57e2298a56cf7a4e774a027905a331f (git); 6.13 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.