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Critical 9.8

Vulnerability in Kernel

CVE-2025-40212 First seen on SecPulse

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-2025-40212 has been found in Kernel.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade Kernel to 6.12.59, 6.17.9 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-40212" on the vendor's site.

CVE-2025-40212 (Kernel) — CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 6.12.59, 6.17.9 — apply immediately
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.

What is the problem

A vulnerability (unclassified) exists in Kernel.

Affected scope

Check the vendor advisory for the affected versions of Kernel.

Severity

Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.

How to fix

Update to 6.12.59, 6.17.9.

Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposureidentify
    grep -r 'Kernel' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Kernel を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patchpatch
    Upgrade Kernel to 6.12.59, 6.17.9

    ステージング環境で 6.12.59, 6.17.9 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verificationverify
    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

EcosystemPackageAffectedFixed
Linux Kernel
≥ 6.12.0, < 6.12.59
≥ 6.13.0, < 6.17.9
6.12.59
6.17.9

Fix status by distribution

Fixed packages published by each distribution for this CVE

Original description The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix refcount leak in nfsd_set_fh_dentry()

nfsd exports a "pseudo root filesystem" which is used by NFSv4 to find
the various exported filesystems using LOOKUP requests from a known root
filehandle. NFSv3 uses the MOUNT protocol to find those exported
filesystems and so is not given access to the pseudo root filesystem.

If a v3 (or v2) client uses a filehandle from that filesystem,
nfsd_set_fh_dentry() will report an error, but still stores the export
in "struct svc_fh" even though it also drops the reference (exp_put()).
This means that when fh_put() is called an extra reference will be dropped
which can lead to use-after-free and possible denial of service.

Normal NFS usage will not provide a pseudo-root filehandle to a v3
client. This bug can only be triggered by the client synthesising an
incorrect filehandle.

To fix this we move the assignments to the svc_fh later, after all
possible error cases have been detected.

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

References

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