CVE-2025-38085: Debian Linux

Medium severity, CVSS 4.7. EPSS: 0.1% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race huge_pmd_unshare() drops a reference on a page table that may have previously been shared across processes, potentially turning it into a normal page table used in another process in which unrelated VMAs can afterwards be installed. If this happens in the middle of a concurrent gup_fast(), gup_fast() could end up walking the page tables of another process. While I don't see any way in which that immediately leads to kernel memory corruption, it is really weird and unexpected. Fix it with an explicit broadcast IPI through tlb_remove_table_sync_one(), just like we do in khugepaged when removing page tables for a THP collapse.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 2.6.20, before 5.10.239 (fixed in 5.10.239); from 5.11, before 5.15.186 (fixed in 5.15.186); from 5.16, before 6.1.142 (fixed in 6.1.142); from 6.2, before 6.6.95 (fixed in 6.6.95); from 6.7, before 6.12.35 (fixed in 6.12.35); from 6.13, before 6.15.4 (fixed in 6.15.4)

Published 2025-06-28. Last modified 2026-07-30.