The iblock module in the Linux kernel incorrectly performs a callback capability check for PREEMPT, PREEMPT_AND_ABORT, and RELEASE operations. When these operations are requested on a device that has not implemented the ops->pr_clear callback, the NULL check is bypassed, leading to a NULL function pointer dereference. This causes a kernel panic, immediately stopping system operation and delivering a denial‑of‑service.

All Linux kernel releases incorporating the iblock SCSI target module prior to the commit that adds the missing NULL check are vulnerable. Because the vendor information lists only the generic Linux kernel, any distribution or custom build that has not applied the patch is considered at risk. No specific version numbers are supplied in the advisory, so a best‑effort assessment requires reviewing the kernel changelog for the iblock module.

The CVSS score for this vulnerability is 7.5, but the EPSS indicates a low likelihood of exploitation (EPSS score of <1%), making precise quantification difficult. The issue is not listed in the CISA KEV catalog, and no public exploits have been disclosed. The likely attack vector is local: an attacker must issue a SCSI PREEMPT or RELEASE command to an iblock device, which typically requires privileged or authenticated access to the target. Because the conditions are narrowly defined, the exploitation likelihood is low, but the impact of a kernel crash is catastrophic, warranting immediate patching.