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

Status: published. Published: 2026-04-22. Updated: 2026-11-05.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780; < a58d298a83a3a9b7ca99ded9d60a1e77231159ef (affected, git); ≥ f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780; < 95c899cd791803a5bf7b73e5994fbbe1cc1a9c36 (affected, git); ≥ f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780; < 7f4e3233faa8470dd0627bc49b2809f2bfebd909 (affected, git); ≥ f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780; < 99a8b420f3f0e162eb9c9c9253929d4d23f9bd30 (affected, git); ≥ f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780; < 0738d395aab8fae3b5a3ad3fc640630c91693c27 (affected, git). Source: CNA: Linux
- Linux / Linux: 6.4 (affected); ≥ 0; < 6.4 (unaffected, semver); ≥ 6.6.131; ≤ 6.6.* (unaffected, semver); ≥ 6.12.80; ≤ 6.12.* (unaffected, semver); ≥ 6.18.21; ≤ 6.18.* (unaffected, semver); ≥ 6.19.11; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.12% as of 2026-11-05; percentile 2.00%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/a58d298a83a3a9b7ca99ded9d60a1e77231159ef (CNA: Linux)

- https://git.kernel.org/stable/c/95c899cd791803a5bf7b73e5994fbbe1cc1a9c36 (CNA: Linux)

- https://git.kernel.org/stable/c/7f4e3233faa8470dd0627bc49b2809f2bfebd909 (CNA: Linux)

- https://git.kernel.org/stable/c/99a8b420f3f0e162eb9c9c9253929d4d23f9bd30 (CNA: Linux)

- https://git.kernel.org/stable/c/0738d395aab8fae3b5a3ad3fc640630c91693c27 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-31482; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-31482; retrieved 2026-11-05; source updated Not reported

Revision: 231ac5d0b8c64b6f91f64594e38fc38d7ce2e84db065810eff9399e368882cd7

Canonical: https://y2.dev/cve/CVE-2026-31482

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