Vulnerability in Linux kernel (CVE-2026-89667)
Summary
Vulnerability in Linux kernel (CVE-2026-89667). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
nfsd: close shrinker/GC/fsnotify vs per-net shutdown race in filecache
The shrinker, GC worker, and fsnotify/lease callbacks can unhash an
nfsd_file from the rhashtable and then call
nfsd_file_dispose_list_delayed() to move it to the per-net dispose list.
If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk
misses the already-unhashed file, and its drain of the per-net dispose
list can run before the file has been queued. The file then sits on
the per-net list with no thread to drain it, leaking both the file and
its associated state.
The GC worker and shrinker already hold nfsd_gc_lock while walking the
LRU, but in the original code they release it before calling
nfsd_file_dispose_list_delayed(). The fsnotify/lease path
(nfsd_file_close_inode) has no synchronization at all.
Fix this by:
-
Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan()
to cover the nfsd_file_dispose_list_delayed() call. -
Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three
callers of nfsd_file_dispose_list_delayed() hold the lock. -
Adding a spin_lock/unlock(nfsd_gc_lock) barrier in
nfsd_file_cache_shutdown_net() after the purge, so that any
in-progress disposal has fully completed before the per-net list
is drained.
All operations inside the lock are non-sleeping (rhashtable lookups,
atomic bit/refcount ops, list moves, svc_wake_up), so the…
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-2026-89667 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 8.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89667" on the vendor's site.
CVE-2026-89667 (Linux kernel) — CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated / 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 8.1/10). Successful exploitation can lead to full system takeover.
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 git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com