Vulnerability in Linux kernel (CVE-2026-89521)
Summary
Vulnerability in Linux kernel (CVE-2026-89521). Confidential information can be exposed externally.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
sched/core: Handle pick_task() releasing the rq lock
Core scheduling's pick_next_task() breaks when a ->pick_task()
implementation can release the rq lock. The selection state derived on entry
is only valid while the lock is held continuously. Once a pick can drop the
lock, an interleaving selection can invalidate all of it: the single-CPU
fast path can commit an uncookied pick although the core went cookied during
the release, and forceidle committed by the interleaving selection skews the
restarted pass's accounting.
Fix it by restarting the whole selection when a pick returns RETRY_TASK
after releasing the lock: a single restart point above the state derivation
replaces the per-loop restart labels, so a retry picks up state committed by
interleaving selections and accounts and resets forceidle like a fresh
selection would.
need_sync and fi_before latch across retries. Clock validity can't be
re-derived - there is no program-ordered way to tell whether the own and
core rq clocks are still updated after the lock was released, as other
lockers' pin cycles may or may not have invalidated them. When restarting,
clear core_clock_updated so that the sibling loop re-updates the core rq,
and update the own rq clock if invalidated.
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-2026-89521 has been found in Linux kernel.
Confidential information can be exposed externally. CVSS score: 7.3/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89521" on the vendor's site.
CVE-2026-89521 (Linux kernel) — CVSS v3 7.3
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: High (CVSS 7.3/10). Confidential information can be exposed externally.
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。
References
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com