CVE-2025-21696
In the Linux kernel, the following vulnerability has been resolved: mm: clear uffd-wp PTE/PMD state on mremap() When mremap()ing a memory region previously registered with userfaultfd as write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in flag clearing leads to a mismatch between the vma flags (which have uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp cleared). This mismatch causes a subsequent mprotect(PROT_WRITE) to trigger a warning in page_table_check_pte_flags() due to setting the pte to writable while uffd-wp is still set. Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any such mremap() so that the values are consistent with the existing clearing of VM_UFFD_WP. Be careful to clear the logical flag regardless of its physical form; a PTE bit, a swap PTE bit, or a PTE marker. Cover PTE, huge PMD and hugetlb paths.
- CVSS 3.1
- 5.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 17% of CVEs (scores of 2026-10-25)
- Published
- Modified
- Record from
- the NVD, synced
Affected
- linux:linux_kernel