CVE-2026-90153 Linux CVE debrief

Who should care

Linux kernel developers and administrators who use the ksmbd module should review and apply the patch to prevent potential security risks. They should also verify the DACL size validation in the ksmbd module and monitor for potential unauthorized access to the system. Additionally, they should confirm whether affected product deployments exist in managed environments and assign an owner for follow-up. Those responsible for system security and vulnerability

Why it matters

The vulnerability in the Linux kernel's ksmbd module allows for an out-of-bounds ACE walk in the DACL, potentially leading to unauthorized access. Linux kernel developers and administrators who use the ksmbd module should review and apply the patch to prevent potential security risks.

• Potential unauthorized access to the system
• Need to verify DACL size validation in the ksmbd module
• Potential impact on system security if not patched

Technical summary

The vulnerability is caused by an out-of-bounds ACE walk in the DACL, which can lead to unauthorized access. The vulnerability has been resolved by bounding ACE walks by the DACL's declared size. This fix addresses the issue by ensuring that ACE walks are properly bounded, preventing potential security risks. The ksmbd module in the Linux kernel is affected, and developers should review and apply the patch to prevent potential security risks. The vulnerability was discovered in the Linux kernel's ksmbd module, and the DACL size was not properly validated.

Defensive priority

High

Recommended defensive actions

• Review and apply the patch to the Linux kernel's ksmbd module
• Verify the DACL size validation in the ksmbd module
• Monitor for potential unauthorized access to the system
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• 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.

Evidence notes

The vulnerability was discovered in the Linux kernel's ksmbd module. The DACL size is not properly validated, allowing for an out-of-bounds ACE walk. The vulnerability has been resolved by bounding ACE walks by the DACL's declared size.

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.