CVE-2026-90155 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, Linux distribution maintainers, and system administrators responsible for updating and patching Linux kernels. They should review and apply patches, update Linux kernels, and monitor system logs for potential exploitation attempts.

Why it matters

Linux kernel developers and maintainers should review and apply patches. System administrators should update Linux kernels and monitor system logs.

• Local attackers may be able to trigger a system crash.
• The vulnerability requires verification of affected versions and potential exploitation.
• System administrators should prioritize patching vulnerable systems.

Technical summary

The ksmbd module in the Linux kernel did not properly detach blocked lock requests before freeing them, leading to a potential BUG_ON() assertion. This vulnerability can be triggered locally, potentially leading to a system crash. The vulnerability requires verification of affected versions and potential exploitation. Linux kernel developers and maintainers should review and apply patches. System administrators should update Linux kernels and monitor system logs for potential exploitation attempts. The ksmbd_file reference count does not cover that graph.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patches provided by the Linux kernel maintainers.
• Ensure that the Linux kernel is updated to a version that includes the fix.
• Monitor system logs for potential exploitation attempts.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• 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.

Evidence notes

The CVE record and source item provide details about the vulnerability, including its description and affected versions. The vulnerability is in the ksmbd module of the Linux kernel. The source item and CVE record provide information on the vulnerability. The vulnerability allows local attackers to trigger a BUG_ON() assertion. The ksmbd_file reference count does not cover the VFS blocked-request graph.

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.