CVE-2026-64103 Linux CVE debrief

Who should care

Linux kernel developers and users, as well as anyone responsible for maintaining and securing Linux-based systems, should be aware of this vulnerability. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Technical summary

The isci driver in the Linux kernel did not properly kill the ISCI completion tasklet during device removal. This could lead to a use-after-free condition, potentially allowing an attacker to execute arbitrary code or cause a denial of service. The vulnerability is caused by the lack of a tasklet_kill() call after wait_for_stop() in the isci_host_deinit() function. This allows the tasklet to still be scheduled and execute after the host has been torn down, leading to a use-after-free condition. The issue can be resolved by adding a tasklet_kill() call after quiescing the scheduling source.

Defensive priority

High

Recommended defensive actions

• Apply the patch to kill the completion tasklet after quiescing the scheduling source
• Ensure that the Linux kernel is updated to a version that includes the fix
• Monitor systems for potential exploitation attempts
• 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 vulnerability was introduced due to the lack of a tasklet_kill() call after wait_for_stop() in the isci_host_deinit() function. This allows the tasklet to still be scheduled and execute after the host has been torn down, leading to a use-after-free condition. The issue can be resolved by adding a tasklet_kill() call after quiescing the scheduling source. The affected product scope and severity should be reviewed, and vendor guidance should be followed for updates or mitigations.

Official resources