CVE-2026-31482 s390/entry: Scrub r12 register on kernel entry
An attacker could potentially read sensitive kernel memory via the unscrubbed r12 register on s390 architecture due to missing register clearing.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31482?
CVE-2026-31482 is a medium-severity vulnerability in Linux kernel, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
s390/entry: Scrub r12 register on kernel entry
Before commit f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP"), all entry handlers loaded r12 with the current task pointer (lg %r12,__LC_CURRENT) for use by the BPENTER/BPEXIT macros. That commit removed TIF_ISOLATE_BP, dropping both the branch prediction macros and the r12 load, but did not add r12 to the register clearing sequence.
Add the missing xgr %r12,%r12 to make the register scrub consistent across all entry points.
Which versions are affected by CVE-2026-31482?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31482?
Apply the vendor's patch.
Is CVE-2026-31482 being exploited?
There is no known exploitation of CVE-2026-31482 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31482, DEBIAN-CVE-2026-31482, GHSA-2rvp-wpqf-89pf, ROOT-OS-DEBIAN-13-CVE-2026-31482, ROOT-OS-UBUNTU-2404-CVE-2026-31482, UBUNTU-CVE-2026-31482.