Vulnerability in Linux kernel (CVE-2026-89711)
Summary
Vulnerability in Linux kernel (CVE-2026-89711). 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:
NFSD: remove flawed WARN_ON_ONCE from nfsd_mode_check
The header for commit e75b23f9e323 ("nfsd: check d_can_lookup in
fh_verify of directories") details the assumption that justified
adding the WARN_ON_ONCE to nfsd_mode_check(), that assumption is
invalid (in the case of NFS reexport).
When NFSD exports an NFS filesystem it is very possible for
nfsd_mode_check() to encounter a @dentry that doesn't have
i_op->lookup (see nfs_fhget()'s NFS_ATTR_FATTR_MOUNTPOINT and
NFS_ATTR_FATTR_V4_REFERRAL handling, and d_flags_for_inode()).
So remove nfsd_mode_check()'s WARN_ON_ONCE(). The nfserr_notdir
return on that branch must stay. It guards the subsequent
lookup_one_unlocked() -> __lookup_slow() path, which calls
inode->i_op->lookup() with no NULL check, so returning nfserr_notdir
is what keeps a client LOOKUP into such a @dentry from dereferencing
a NULL method pointer.
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-2026-89711 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 8.2/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89711" on the vendor's site.
CVE-2026-89711 (Linux kernel) — CVSS v3 8.2
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 8.2/10). 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。
References
- 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 nvd.nist.gov
- web github.com