CVE-2026-97564 Linux CVE debrief

Who should care

Linux kernel administrators and users, particularly those responsible for managing and securing Linux kernel deployments, should be aware of this vulnerability and take necessary precautions to mitigate its impact. Verify kernel version and check for cifs.idmap key restrictions. Check for potential security issues with cifs.idmap keys. Review system for potential security issues with cifs.idmap keys.

Why it matters

The Linux kernel has a vulnerability that allows userspace to create cifs.idmap keys with authority-bearing fields. This can lead to a potential security issue when a root usermodehelper upcall consumes the unvetted description in root context.

• Verify kernel version and check for cifs.idmap key restrictions
• Check for potential security issues with cifs.idmap keys

Technical summary

The Linux kernel has a vulnerability that allows userspace to create cifs.idmap keys with authority-bearing fields. This can lead to a potential security issue when a root usermodehelper upcall consumes the unvetted description in root context. Only accept cifs.idmap descriptions while CIFS is using its private root_cred to request the key. id_to_sid()/sid_to_id() already run under override_creds(root_cred), so the kernel-originated path is unaffected. This mirrors commit 3da1fdf4efbc (smb: client: reject userspace cifs.spnego descriptions), which applied the same restriction to cifs.spnego. Linux kernel administrators and users should verify the kernel version and check for cifs.idmap key restrictions.

Defensive priority

Verify kernel version and check for cifs.idmap key restrictions

Recommended defensive actions

• Verify kernel version and check for cifs.idmap key restrictions
• Check for CIFS private root_cred usage
• Review system for potential security issues with cifs.idmap keys
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record and NVD entry provide information on the vulnerability, but details on exploitation and impact are limited. The Linux kernel has a vulnerability that allows userspace to create cifs.idmap keys with authority-bearing fields. This can lead to a potential security issue when a root usermodehelper upcall consumes the unvetted description in root context. Verify kernel version and check for cifs.idmap key restrictions. Check for potential security issues with cifs.idmap keys. The vulnerability is related to the cifs.idmap ke

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.