---
id: CVE-2025-68171
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/fpu: Ensure XFD state on signal delivery

  Sean reported [1] the following splat when running KVM tests:

     WARNING: CPU: 232 PID: 15391 at xfd_validate_state+0x65/…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  x86/fpu: Ensure XFD state on signal delivery

  Sean reported [1] the following splat when running KVM tests:

     WARNING: CPU: 232 PID: 15391 at xfd_validate_state+0x65/…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-821
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 672365477ae8afca5a1cca98c1deb733235e4525 <
    eefbfb722042fc9210d2e0ac2b063fd1abf51895
  - >-
    Linux >= 672365477ae8afca5a1cca98c1deb733235e4525 <
    1811c610653c0cd21cc9add14595b7cffaeca511
  - >-
    Linux >= 672365477ae8afca5a1cca98c1deb733235e4525 <
    5b2619b488f1d08b960c43c6468dd0759e8b3035
  - >-
    Linux >= 672365477ae8afca5a1cca98c1deb733235e4525 <
    3f735419c4b43cde42e6d408db39137b82474e31
  - >-
    Linux >= 672365477ae8afca5a1cca98c1deb733235e4525 <
    388eff894d6bc5f921e9bfff0e4b0ab2684a96e9
  - Linux 5.16
published: '2025-12-16'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:19:09.510'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68171'
references:
  - url: 'https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-68171.json
  - url: 'https://access.redhat.com/security/cve/CVE-2025-68171'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2422683'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2025-68171'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68171'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2025121628-CVE-2025-68171-d43d@gregkh/T
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00154
epssPercentile: 0.04476
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:59:46.341192Z'
scores:
  nvd: 7.8
  vendor: 5.5
ingestedAt: '2026-10-14T13:30:58.443Z'
---

## Overview

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

x86/fpu: Ensure XFD state on signal delivery

Sean reported [1] the following splat when running KVM tests:

   WARNING: CPU: 232 PID: 15391 at xfd_validate_state+0x65/0x70
   Call Trace:
    <TASK>
    fpu__clear_user_states+0x9c/0x100
    arch_do_signal_or_restart+0x142/0x210
    exit_to_user_mode_loop+0x55/0x100
    do_syscall_64+0x205/0x2c0
    entry_SYSCALL_64_after_hwframe+0x4b/0x53

Chao further identified [2] a reproducible scenario involving signal
delivery: a non-AMX task is preempted by an AMX-enabled task which
modifies the XFD MSR.

When the non-AMX task resumes and reloads XSTATE with init values,
a warning is triggered due to a mismatch between fpstate::xfd and the
CPU's current XFD state. fpu__clear_user_states() does not currently
re-synchronize the XFD state after such preemption.

Invoke xfd_update_state() which detects and corrects the mismatch if
there is a dynamic feature.

This also benefits the sigreturn path, as fpu__restore_sig() may call
fpu__clear_user_states() when the sigframe is inaccessible.

[ dhansen: minor changelog munging ]

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-68171.json)