The Linux kernel for s390 processors fails to clear the r12 register when entering kernel mode. A prior commit removed the load of the current task pointer into r12 and the patch that should have scrubbed this value was omitted. The lingering register contents may expose a pointer to the current task, allowing a local attacker to read or infer sensitive kernel data.

All Linux kernel releases for s390 hardware that do not include the commit adding the r12 register clearing. No specific kernel version numbers are listed in the advisory, so any older kernel lacking the patch is potentially affected.

No EPSS score and the vulnerability is not listed in CISA KEV, indicating an uncertain exploitation probability. Because the flaw involves a register only manipulated during kernel entry, the attack vector is presumably local or requires elevated privileges. The absence of a CVSS score means the exact severity cannot be quantified, but the potential for information leakage exists.