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Fencer Intel
high 7.8

CVE-2026-63875 json

arm64: tlb: Flush walk cache when unsharing PMD tables

published 3mo ago modified 12d ago also EUVD-2026-45760

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 7%
public exploits
0
none known

Summary

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

arm64: tlb: Flush walk cache when unsharing PMD tables

When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only).

This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks.

Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated.

Here is the detailed distinction between vae1is and vale1is:

| Instruction Combination | Actual Invalidation Scope | | ------------------------ | --------------------------------------------------| | `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) | | `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 | | `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) | | `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only |

Patch / fix

  • Linux Linux 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-63875

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux Ubuntu 24.04 LTS 6.8.0-146.146
  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1066.69
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1070.78

ubuntu advisories UBUNTU-CVE-2026-63875

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 9 5.14.0-687.53.1.el9_8
  • rv RHEL 9 5.14.0-687.53.1.el9_8
  • perf RHEL 9 5.14.0-687.53.1.el9_8
  • rtla RHEL 9 5.14.0-687.53.1.el9_8
  • libperf RHEL 9 5.14.0-687.53.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.53.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.53.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.53.1.el9_8

red hat advisories RHSA-2026:72623RHSA-2026:72467RHSA-2026:72468

  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.37.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.37.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1.160000.2.19
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-azure SLES 16.0, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-obs-qa SLES 16.0, SLES for SAP applications 16.0 6.12.0-160000.37.1

suse advisories SUSE-SU-2026:23237-1SUSE-SU-2026:23068-1SUSE-SU-2026:23221-1SUSE-SU-2026:23231-1SUSE-SU-2026:23066-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1

  • kernel-rt AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-core AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel-rt-debug-modules-extra AlmaLinux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel AlmaLinux 8 4.18.0-553.169.1.el8_10

almalinux advisories ALSA-2026:72467ALSA-2026:72468ALSA-2026:72623

  • kernel Rocky Linux 9 5.14.0-687.53.1.el9_8
  • kernel-rt Rocky Linux 8 4.18.0-553.169.1.rt7.510.el8_10
  • kernel Rocky Linux 8 4.18.0-553.169.1.el8_10

rocky linux advisories RLSA-2026:72623RLSA-2026:72467RLSA-2026:72468

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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-2026-63875 updated cvss 7.0

kernel: arm64: tlb: Flush walk cache when unsharing PMD tables

  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.53.1.el9_8, perf 5.14.0-687.53.1.el9_8, rtla 5.14.0-687.53.1.el9_8, python3-perf 5.14.0-687.53.1.el9_8, kernel-devel-matched 5.14.0-687.53.1.el9_8, kernel-64k-devel-matched 5.14.0-687.53.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:72623
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) rv 5.14.0-427.161.1.el9_4, perf 5.14.0-427.161.1.el9_4, rtla 5.14.0-427.161.1.el9_4, kernel-devel-matched 5.14.0-427.161.1.el9_4, kernel-64k-devel-matched 5.14.0-427.161.1.el9_4, kernel-debug-devel-matched 5.14.0-427.161.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:94109
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.169.1.el8_10, kernel 4.18.0-553.169.1.el8_10, bpftool 4.18.0-553.169.1.el8_10, kernel-core 4.18.0-553.169.1.el8_10, kernel-tools 4.18.0-553.169.1.el8_10, python3-perf 4.18.0-553.169.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:72468
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.53.1.el9_8, kernel-64k 5.14.0-687.53.1.el9_8, kernel-core 5.14.0-687.53.1.el9_8, kernel-tools 5.14.0-687.53.1.el9_8, kernel-modules 5.14.0-687.53.1.el9_8, kernel-64k-core 5.14.0-687.53.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:72623
  • Red Hat Enterprise Linux BaseOS E4S (v.9.4) bpftool 7.3.0-427.161.1.el9_4, kernel 5.14.0-427.161.1.el9_4, kernel-64k 5.14.0-427.161.1.el9_4, kernel-core 5.14.0-427.161.1.el9_4, kernel-tools 5.14.0-427.161.1.el9_4, python3-perf 5.14.0-427.161.1.el9_4, +28 more
    fixed: vendor fix RHSA-2026:94109
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.53.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.53.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.53.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.53.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.53.1.el9_8
    fixed: vendor fix RHSA-2026:72623
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.169.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.169.1.el8_10
    fixed: vendor fix RHSA-2026:72468
show 7 more
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-kvm 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, +4 more
    fixed: vendor fix RHSA-2026:72467
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.53.1.el9_8, kernel-rt-64k 5.14.0-687.53.1.el9_8, kernel-rt-core 5.14.0-687.53.1.el9_8, kernel-rt-modules 5.14.0-687.53.1.el9_8, kernel-rt-64k-core 5.14.0-687.53.1.el9_8, kernel-rt-debug-core 5.14.0-687.53.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:72623
  • Red Hat Enterprise Linux Real Time E4S (v.9.4) kernel-rt 5.14.0-427.161.1.el9_4, kernel-rt-core 5.14.0-427.161.1.el9_4, kernel-rt-modules 5.14.0-427.161.1.el9_4, kernel-rt-debug-core 5.14.0-427.161.1.el9_4, kernel-rt-modules-core 5.14.0-427.161.1.el9_4, kernel-rt-debug-modules 5.14.0-427.161.1.el9_4, +4 more
    fixed: vendor fix RHSA-2026:94109
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.53.1.el9_8, kernel-rt-core 5.14.0-687.53.1.el9_8, kernel-rt-modules 5.14.0-687.53.1.el9_8, kernel-rt-debug-core 5.14.0-687.53.1.el9_8, kernel-rt-modules-core 5.14.0-687.53.1.el9_8, kernel-rt-debug-modules 5.14.0-687.53.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:72623
  • Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4) kernel-rt 5.14.0-427.161.1.el9_4, kernel-rt-kvm 5.14.0-427.161.1.el9_4, kernel-rt-core 5.14.0-427.161.1.el9_4, kernel-rt-modules 5.14.0-427.161.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.161.1.el9_4, kernel-rt-debug-core 5.14.0-427.161.1.el9_4, +6 more
    fixed: vendor fix RHSA-2026:94109
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-core 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-debug-modules 4.18.0-553.169.1.rt7.510.el8_10, kernel-rt-modules-extra 4.18.0-553.169.1.rt7.510.el8_10, +2 more
    fixed: vendor fix RHSA-2026:72467
  • 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 10 kernel
    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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
26d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

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

Weakness
  • CWE-459 Incomplete Cleanup
  • CWE-670 Always-Incorrect Control Flow Implementation
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.