Vulnerability in Linux kernel (CVE-2026-89723)
Summary
Vulnerability in Linux kernel (CVE-2026-89723). 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:
nilfs2: fix slab-out-of-bounds in nilfs_direct_propagate after truncation
Shuangpeng Bai reported that KASAN detected a slab-out-of-bounds error
in nilfs_direct_propagate() during testing.
Analysis revealed that after truncating a file, a node block immediately
below the B-tree root was not deleted. Instead, it remained in the B-tree
node cache in a dirty state. The log writer subsequently detected this
block and incorrectly invoked nilfs_direct_propagate() on it, which is
designed to handle only data blocks in direct mapping.
B-tree nodes in the cache are managed by virtual block numbers, and their
logical keys typically exceed the range expected by direct mapping.
Consequently, processing such a node as a direct mapping entry triggers
a slab-out-of-bounds access.
The root cause is that when a B-tree mapping collapses into a direct
mapping during truncation, an intermediate node block pointed to by the
root node is left behind as garbage instead of being explicitly deleted.
This resolves the issue by adding a nilfs_btree_discard() operation
to delete the remaining intermediate node block during the conversion.
A 'deform' flag is added to the bop_delete interface to explicitly signal
that the deletion is part of a mapping transformation. This allows the
B-tree mapping implementation to perform the necessary cleanup and
discarding of the residual node structure that would be otherwise be left
orphaned…
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-2026-89723 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89723" on the vendor's site.
CVE-2026-89723 (Linux kernel) — CVSS v3 7.8
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 7.8/10). 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 git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com