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high 7.8

CVE-2025-40006 json

mm/hugetlb: fix folio is still mapped when deleted

published last yr. modified 21d ago also EUVD-2025-35074

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

mm/hugetlb: fix folio is still mapped when deleted

Migration may be raced with fallocating hole. remove_inode_single_folio will unmap the folio if the folio is still mapped. However, it's called without folio lock. If the folio is migrated and the mapped pte has been converted to migration entry, folio_mapped() returns false, and won't unmap it. Due to extra refcount held by remove_inode_single_folio, migration fails, restores migration entry to normal pte, and the folio is mapped again. As a result, we triggered BUG in filemap_unaccount_folio.

The log is as follows: BUG: Bad page cache in process hugetlb pfn:156c00 page: refcount:515 mapcount:0 mapping:0000000099fef6e1 index:0x0 pfn:0x156c00 head: order:9 mapcount:1 entire_mapcount:1 nr_pages_mapped:0 pincount:0 aops:hugetlbfs_aops ino:dcc dentry name(?):"my_hugepage_file" flags: 0x17ffffc00000c1(locked|waiters|head|node=0|zone=2|lastcpupid=0x1fffff) page_type: f4(hugetlb) page dumped because: still mapped when deleted CPU: 1 UID: 0 PID: 395 Comm: hugetlb Not tainted 6.17.0-rc5-00044-g7aac71907bde-dirty #484 NONE Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 Call Trace: <TASK> dump_stack_lvl+0x4f/0x70 filemap_unaccount_folio+0xc4/0x1c0 __filemap_remove_folio+0x38/0x1c0 filemap_remove_folio+0x41/0xd0 remove_inode_hugepages+0x142/0x250 hugetlbfs_fallocate+0x471/0x5a0 vfs_fallocate+0x149/0x380

Hold folio lock before checking if the folio is mapped to avold race with migration.

Patch / fix

  • Linux Linux 5.4.300, 5.10.245, 5.15.194, 6.1.155, 6.6.109, 6.12.50, 6.16.10, 6.17
  • linux Debian 12 6.1.158-1
  • linux Debian 13 6.12.57-1
  • linux Debian 14 6.16.10-1

debian advisories DEBIAN-CVE-2025-40006

  • linux Ubuntu 22.04 LTS 5.15.0-170.180
  • linux Ubuntu 24.04 LTS 6.8.0-106.106
  • linux Ubuntu 25.10 6.17.0-6.6
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1100.107
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1050.53
  • linux-aws Ubuntu 25.10 6.17.0-1003.3
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1100.109
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1052.55

ubuntu advisories UBUNTU-CVE-2025-40006

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-40.1
  • kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1
  • kernel-default-base Linux Micro 6.1, Linux Micro 6.0 6.4.0-39.1.21.16
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.28.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.28.1

suse advisories SUSE-SU-2026:20845-1SUSE-SU-2026:20876-1SUSE-SU-2026:20477-1SUSE-SU-2026:20498-1SUSE-SU-2026:0316-1SUSE-SU-2026:0315-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.8.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.8.1
  • kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.8.1

opensuse advisories openSUSE-SU-2025:20172-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-40006 updated cvss 4.7

kernel: mm/hugetlb: fix folio is still mapped when deleted

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9, openshift/ose-rhel-coreos-10
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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