Vulnerability in Linux kernel (CVE-2026-43227)
Summary
Vulnerability in Linux kernel (CVE-2026-43227). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
clocksource/drivers/sh_tmu: Always leave device running after probe
The TMU device can be used as both a clocksource and a clockevent
provider. The driver tries to be smart and power itself on and off, as
well as enabling and disabling its clock when it's not in operation.
This behavior is slightly altered if the TMU is used as an early
platform device in which case the device is left powered on after probe,
but the clock is still enabled and disabled at runtime.
This has worked for a long time, but recent improvements in PREEMPT_RT
and PROVE_LOCKING have highlighted an issue. As the TMU registers itself
as a clockevent provider, clockevents_register_device(), it needs to use
raw spinlocks internally as this is the context of which the clockevent
framework interacts with the TMU driver. However in the context of
holding a raw spinlock the TMU driver can't really manage its power
state or clock with calls to pm_runtime_() and clk_() as these calls
end up in other platform drivers using regular spinlocks to control
power and clocks.
This mix of spinlock contexts trips a lockdep warning.
=============================
[ BUG: Invalid wait context ]
6.18.0-arm64-renesas-09926-gee959e7c5e34 #1 Not tainted
-----------------------------
swapper/0/0 is trying to lock:
ffff000008c9e180 (&dev->power.lock){-...}-{3:3}, at: __pm_runtime_resume+0x38/0x88
other info that might help us debug…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-43227 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-43227" on the vendor's site.
CVE-2026-43227 (Linux kernel) — CVSS v3 5.5
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-43227 linux-lts Fixed in: 6.1.167-r0
- Debian DEBIAN-CVE-2026-43227 linux Fixed in: 5.10.257-1
- Ubuntu UBUNTU-CVE-2026-43227 linux
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com