CVE-2025-71111 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators, especially those using affected versions, should assess exposure and apply patches. Affected operators, platform administrators, vulnerability-management teams, and security teams should review system configurations to ensure they are not using affected versions of the Linux kernel and apply patches provided by the Linux kernel maintainers.

Why it matters

CVE-2025-71111 is a medium-severity vulnerability in the Linux kernel that requires verification of exposure and application of patches to prevent potential issues.

• Verification of system configurations and versions is necessary to determine exposure.
• Applying patches provided by the Linux kernel maintainers is crucial to prevent potential divide-by-zero errors.
• Maintainers and users should review system configurations to ensure they are not using affected versions of the Linux kernel.

Technical summary

The Linux kernel vulnerability, CVE-2025-71111, involves a TOCTOU race condition in the w83791d hwmon driver. The flaw arises from a macro, FAN_FROM_REG, which evaluates its arguments multiple times. This can lead to divide-by-zero errors in lockless contexts. The fix involves converting the macro to a static function to ensure arguments are evaluated only once. Additionally, the calculation of minimum limits was moved inside an update lock to ensure data consistency.

Defensive priority

Medium priority for Linux kernel maintainers and users, especially those using affected versions, to apply patches and assess exposure.

Recommended defensive actions

• Apply patches provided by the Linux kernel maintainers to affected systems.
• Assess exposure by reviewing system configurations and versions.
• Verify system configurations against known vulnerable versions.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, its impact, and patches. Multiple patch references are available, indicating a fix has been applied to the Linux kernel. Linux kernel maintainers and users should verify exposure by reviewing system configurations and versions, and apply patches provided by the Linux kernel maintainers to affected systems. The vulnerability's impact and patches are documented in various sources, including the official CVE Program record and NIST NVD detail page.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.