CVE-2025-38084mm/hugetlb: unshare page tables during VMA split, not before
Updated under an hour ago ()
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It affects Linux and 2 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: unshare page tables during VMA split, not before Currently, __split_vma() triggers hugetlb page table unsharing through vm_ops->may_split(). This happens before the VMA lock and rmap locks are taken - which is too early, it allows racing VMA-locked page faults in our process and racing rmap walks from other processes to cause page tables to be shared again before we actually perform the split. Fix it by explicitly calling into the hugetlb unshare logic from __split_vma() in the same place where THP splitting also happens. At that point, both the VMA and the rmap(s) are write-locked. An annoying detail is that we can now call into the helper hugetlb_unshare_pmds() from two different locking contexts: 1. from hugetlb_split(), holding: - mmap lock (exclusively) - VMA lock - file rmap lock (exclusively) 2. hugetlb_unshare_all_pmds(), which I think is designed to be able to call us with only the mmap lock held (in shared mode), but currently only runs while holding mmap lock (exclusively) and VMA lock Backporting note: This commit fixes a racy protection that was introduced in commit b30c14cd6102 ("hugetlb: unshare some PMDs when splitting VMAs"); that commit claimed to fix an issue introduced in 5.13, but it should actually also go all the way back. [jannh@google.com: v2]
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | from 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa before e8847d18cd9fff1edbb45e963d9141273c3b539c; from 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa before 366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0; from 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa before 2511ac64bc1617ca716d3ba8464e481a647c1902; from 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa before af6cfcd0efb7f051af221c418ec8b37a10211947; 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa builds before 9cf5b2a3b72c23fb7b84736d5d19ee6ea718762b; 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa builds before 8a21d5584826f4880f45bbf8f72375f4e6c0ff2a; from 39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa before 081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0 | CNA record |
linux linux_kernel linux:linux_kernel | from 2.6.20 before 5.10.239; from 5.11 before 5.15.186; from 5.16 before 6.1.142; from 6.2 before 6.6.95; from 6.7 before 6.12.35; from 6.13 before 6.15.4 | NVD |
debian debian_linux debian:debian_linux | 11.0 | NVD |
References
- https://git.kernel.org/stable/c/e8847d18cd9fff1edbb45e963d9141273c3b539cpatch
- https://git.kernel.org/stable/c/366298f2b04d2bf1f2f2b7078405bdf9df9bd5d0patch
- https://git.kernel.org/stable/c/2511ac64bc1617ca716d3ba8464e481a647c1902patch
- https://git.kernel.org/stable/c/af6cfcd0efb7f051af221c418ec8b37a10211947patch
- https://git.kernel.org/stable/c/9cf5b2a3b72c23fb7b84736d5d19ee6ea718762bpatch
- https://git.kernel.org/stable/c/8a21d5584826f4880f45bbf8f72375f4e6c0ff2apatch
- https://git.kernel.org/stable/c/081056dc00a27bccb55ccc3c6f230a3d5fd3f7e0patch
- https://project-zero.issues.chromium.org/issues/420715744third-party-advisory
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlthird-party-advisory
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlthird-party-advisory
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.