CVE-2025-38085 | mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race

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.

Published: 2025-06-28 Last update: 2025-12-18 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Conclusion & alert: CVE-2025-38085 is rated Low Risk (27.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.08%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-38085

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-24 0.03% 0.08% +0.05%
2 2025-12-19 0.05% 0.03% -0.02%
3 2025-10-17 0.05%

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38085

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
1.0 3.6 [email protected]

Weakness enumeration for CVE-2025-38085

OS Trackers for CVE-2025-38085

vendor priority summary link
debian not yet assigned CVE-2025-38085 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-38085
redhat medium https://access.redhat.com/security/cve/CVE-2025-38085
suse medium https://www.suse.com/security/cve/CVE-2025-38085/
ubuntu medium CVE-2025-38085 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 170, ignored 168, needed 44, not-affected 21, needs-triage 2, pending 1. https://ubuntu.com/security/CVE-2025-38085

Affected software / configurations for CVE-2025-38085

Vendor Product Version Raw CPE
linux linux_kernel >= 2.6.20, < 5.10.239 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.186 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.142 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.95 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.35 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.15.4 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-38085

URL Tags
https://git.kernel.org/stable/c/034a52b5ef57c9c8225d94e9067f3390bb33922f Patch
https://git.kernel.org/stable/c/1013af4f585fccc4d3e5c5824d174de2257f7d6d Patch
https://git.kernel.org/stable/c/952596b08c74e8fe9e2883d1dc8a8f54a37384ec Patch
https://git.kernel.org/stable/c/a3d864c901a300c295692d129159fc3001a56185 Patch
https://git.kernel.org/stable/c/a6bfeb97941a9187833b526bc6cc4ff5706d0ce9 Patch
https://git.kernel.org/stable/c/b7754d3aa7bf9f62218d096c0c8f6c13698fac8b Patch
https://git.kernel.org/stable/c/fe684290418ef9ef76630072086ee530b92f02b8 Patch
https://project-zero.issues.chromium.org/issues/420715744 Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Third Party Advisory
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