CVE-2025-21696mm: clear uffd-wp PTE/PMD state on mremap()
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 5.5 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 21, 2026
- First seen by InfoSec Signals
- Oct 21, 2026
Affected products
Linux Linux linux:linux (from the name) | 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 builds before 8e2f6ba256dd1e590addc48e6e9577bf39c482f2; from 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 before 310ac886d68de661c3a334198d8604b722d7fdf8; 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03 builds before 0cef0bb836e3cfe00f08f9606c72abd72fe78ca3 | CNA record |
linux linux_kernel linux:linux_kernel | from 5.7 before 6.12.11; 6.13; 6.13; 6.13; 6.13; 6.13; 6.13; 6.13 | NVD |
References
- https://git.kernel.org/stable/c/8e2f6ba256dd1e590addc48e6e9577bf39c482f2
- https://git.kernel.org/stable/c/310ac886d68de661c3a334198d8604b722d7fdf8patch
- https://git.kernel.org/stable/c/0cef0bb836e3cfe00f08f9606c72abd72fe78ca3patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.