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CVE-2025-68171
x86/fpu: Ensure XFD state on signal delivery
Description

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 ]

INFO

Published Date :

Dec. 16, 2025, 2:15 p.m.

Last Modified :

Dec. 16, 2025, 2:15 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-68171 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Solution
Ensure XFD state consistency during signal delivery and preemption.
  • Update the Linux kernel to resolve the XFD state issue.
  • Apply the patch for x86/fpu XFD state handling.
  • Synchronize XFD state after task preemption.
  • Invoke xfd_update_state() to correct mismatches.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-68171.

URL Resource
https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511
https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9
https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31
https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035
https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-68171 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-68171 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-68171 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-68171 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Dec. 16, 2025

    Action Type Old Value New Value
    Added Description 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 ]
    Added Reference https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511
    Added Reference https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9
    Added Reference https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31
    Added Reference https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035
    Added Reference https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.