CVE-2026-80724 PUBLISHED

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

Assigner: Linux
Reserved: 26.08.2026 Published: 28.08.2026 Updated: 28.08.2026

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).

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 20503272422693d793b84f88bf23fe4e955d3a33 to 5b4f2bec7bea6c04084d720d731bedee7caf878d (excl.)
  • affected from 20503272422693d793b84f88bf23fe4e955d3a33 to 2496e141827102d6af512950057d402a2cfb2bfc (excl.)
  • affected from 20503272422693d793b84f88bf23fe4e955d3a33 to 2e596e7814ba38cdc129991058b6c254ed37cb11 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 6.13 is affected
  • unaffected from 0 to 6.13 (excl.)
  • unaffected from 6.18.47 to 6.18.* (incl.)
  • unaffected from 7.1.11 to 7.1.* (incl.)
  • unaffected from 7.2.1 to 7.2.* (incl.)

References