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Fencer Intel
medium 5.5

CVE-2026-23375 json

mm: thp: deny THP for files on anonymous inodes

published 7mo ago modified 4mo ago also EUVD-2026-15365

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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

mm: thp: deny THP for files on anonymous inodes

file_thp_enabled() incorrectly allows THP for files on anonymous inodes (e.g. guest_memfd and secretmem). These files are created via alloc_file_pseudo(), which does not call get_write_access() and leaves inode->i_writecount at 0. Combined with S_ISREG(inode->i_mode) being true, they appear as read-only regular files when CONFIG_READ_ONLY_THP_FOR_FS is enabled, making them eligible for THP collapse.

Anonymous inodes can never pass the inode_is_open_for_write() check since their i_writecount is never incremented through the normal VFS open path. The right thing to do is to exclude them from THP eligibility altogether, since CONFIG_READ_ONLY_THP_FOR_FS was designed for real filesystem files (e.g. shared libraries), not for pseudo-filesystem inodes.

For guest_memfd, this allows khugepaged and MADV_COLLAPSE to create large folios in the page cache via the collapse path, but the guest_memfd fault handler does not support large folios. This triggers WARN_ON_ONCE(folio_test_large(folio)) in kvm_gmem_fault_user_mapping().

For secretmem, collapse_file() tries to copy page contents through the direct map, but secretmem pages are removed from the direct map. This can result in a kernel crash:

BUG: unable to handle page fault for address: ffff88810284d000 RIP: 0010:memcpy_orig+0x16/0x130 Call Trace: collapse_file hpage_collapse_scan_file madvise_collapse

Secretmem is not affected by the crash on upstream as the memory failure recovery handles the failed copy gracefully, but it still triggers confusing false memory failure reports:

Memory failure: 0x106d96f: recovery action for clean unevictable LRU page: Recovered

Check IS_ANON_FILE(inode) in file_thp_enabled() to deny THP for all anonymous inode files.

Patch / fix

  • Linux Linux 6.12.78, 6.18.17, 6.19.7, 7.0
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.19.8-1

debian advisories DEBIAN-CVE-2026-23375

  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1061.62
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1063.71
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1046.50
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1061.65

ubuntu advisories UBUNTU-CVE-2026-23375

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 RHEL 10.2 6.12.0-211.18.1.el10_2
  • rv RHEL 10.2 6.12.0-211.18.1.el10_2
  • perf RHEL 10.2 6.12.0-211.18.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.18.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.18.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.18.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.18.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.18.1.el10_2

red hat advisories RHSA-2026:55445RHSA-2026:21557

  • kernel-syms Linux Micro Extras 6.2 6.12.0-160000.33.1
  • kernel-obs-build Linux Micro Extras 6.2 6.12.0-160000.33.1

suse advisories SUSE-SU-2026:21834-1

  • kernel AlmaLinux 10 6.12.0-211.18.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.18.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.18.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.18.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.18.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.18.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.18.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.18.1.el10_2

almalinux advisories ALSA-2026:21557

  • kernel Rocky Linux 10 6.12.0-211.18.1.el10_2

rocky linux advisories RLSA-2026:21557

Is CVE-2026-23375 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-23375 updated cvss 7.0

kernel: mm: thp: deny THP for files on anonymous inodes

  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.18.1.el10_2, perf 6.12.0-211.18.1.el10_2, rtla 6.12.0-211.18.1.el10_2, python3-perf 6.12.0-211.18.1.el10_2, kernel-devel-matched 6.12.0-211.18.1.el10_2, kernel-64k-devel-matched 6.12.0-211.18.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:21557
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.98.1.el10_0, perf 6.12.0-55.98.1.el10_0, rtla 6.12.0-55.98.1.el10_0, python3-perf 6.12.0-55.98.1.el10_0, kernel-devel-matched 6.12.0-55.98.1.el10_0, kernel-64k-devel-matched 6.12.0-55.98.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:55445
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.18.1.el10_2, kernel-64k 6.12.0-211.18.1.el10_2, kernel-core 6.12.0-211.18.1.el10_2, kernel-tools 6.12.0-211.18.1.el10_2, kernel-modules 6.12.0-211.18.1.el10_2, kernel-64k-core 6.12.0-211.18.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:21557
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.98.1.el10_0, kernel-64k 6.12.0-55.98.1.el10_0, kernel-core 6.12.0-55.98.1.el10_0, kernel-tools 6.12.0-55.98.1.el10_0, kernel-modules 6.12.0-55.98.1.el10_0, kernel-64k-core 6.12.0-55.98.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:55445
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.18.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.18.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.18.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.18.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.18.1.el10_2
    fixed: vendor fix RHSA-2026:21557
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.98.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.98.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.98.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.98.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.98.1.el10_0
    fixed: vendor fix RHSA-2026:55445
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.18.1.el10_2, kernel-rt-64k 6.12.0-211.18.1.el10_2, kernel-rt-core 6.12.0-211.18.1.el10_2, kernel-rt-modules 6.12.0-211.18.1.el10_2, kernel-rt-64k-core 6.12.0-211.18.1.el10_2, kernel-rt-debug-core 6.12.0-211.18.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:21557
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.98.1.el10_0, kernel-rt-64k 6.12.0-55.98.1.el10_0, kernel-rt-core 6.12.0-55.98.1.el10_0, kernel-rt-modules 6.12.0-55.98.1.el10_0, kernel-rt-64k-core 6.12.0-55.98.1.el10_0, kernel-rt-debug-core 6.12.0-55.98.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:55445
show 3 more
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.18.1.el10_2, kernel-rt-core 6.12.0-211.18.1.el10_2, kernel-rt-modules 6.12.0-211.18.1.el10_2, kernel-rt-debug-core 6.12.0-211.18.1.el10_2, kernel-rt-modules-core 6.12.0-211.18.1.el10_2, kernel-rt-debug-modules 6.12.0-211.18.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:21557
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.98.1.el10_0, kernel-rt-kvm 6.12.0-55.98.1.el10_0, kernel-rt-core 6.12.0-55.98.1.el10_0, kernel-rt-modules 6.12.0-55.98.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.98.1.el10_0, kernel-rt-debug-core 6.12.0-55.98.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:55445
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more 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
    not affected: vulnerable code not present

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

0.12% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.