In the Linux kernel, the following vulnerability has been resolved: scsi: isci: Fix use-after-free in device removal path The ISCI completion… (CVE-2026-64103)

CVE-2026-64103 is a use-after-free vulnerability in the Linux kernel's ISCI SCSI driver related to the device removal path. The ISCI completion tasklet is initialized and scheduled from interrupt handlers but is not properly killed before teardown continues, allowing interrupts to requeue the tasklet after the device is partially torn down. This race condition can cause the tasklet to run on a freed host structure, leading to use-after-free. The fix involves killing the completion tasklet only after the device stop completion is confirmed, preventing further IRQ-driven scheduling during teardown. This vulnerability affects Linux kernel versions prior to 5.15.0-1112.119~20.04.1 and similar versions as listed. The vulnerability has a CVSS 3.1 score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating local attack vector with low complexity and significant impact on confidentiality, integrity, and availability. Ubuntu has released patches addressing this and other kernel vulnerabilities in their security notices USN-8575-1 and USN-8576-1.

Successful exploitation of this use-after-free vulnerability could allow a local attacker with low privileges to cause memory corruption in the kernel, potentially leading to privilege escalation, system crashes, or arbitrary code execution within the kernel context. The CVSS score of 7.8 reflects high impact on confidentiality, integrity, and availability. However, exploitation requires local access and low complexity, with no user interaction needed.

A patch is available and has been released by Ubuntu as part of their Linux kernel security updates. Users should update their systems to the fixed kernel versions at or beyond 5.15.0-1112.119~20.04.1 or the corresponding patched releases provided by their Linux distribution. After applying the update, a system reboot is required to activate the patched kernel. No additional mitigation steps are necessary as the vulnerability is addressed by the official fix.