Vulnerability in Kernel (CVE-2025-39868)

Summary

Vulnerability in Kernel (CVE-2025-39868). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 6.16.8 or later.

Original description

The description as published by the source.

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

erofs: fix runtime warning on truncate_folio_batch_exceptionals()

Commit 0e2f80afcfa6("fs/dax: ensure all pages are idle prior to
filesystem unmount") introduced the WARN_ON_ONCE to capture whether
the filesystem has removed all DAX entries or not and applied the
fix to xfs and ext4.

Apply the missed fix on erofs to fix the runtime warning:

[ 5.266254] ------------[ cut here ]------------
[ 5.266274] WARNING: CPU: 6 PID: 3109 at mm/truncate.c:89 truncate_folio_batch_exceptionals+0xff/0x260
[ 5.266294] Modules linked in:
[ 5.266999] CPU: 6 UID: 0 PID: 3109 Comm: umount Tainted: G S 6.16.0+ #6 PREEMPT(voluntary)
[ 5.267012] Tainted: [S]=CPU_OUT_OF_SPEC
[ 5.267017] Hardware name: Dell Inc. OptiPlex 5000/05WXFV, BIOS 1.5.1 08/24/2022
[ 5.267024] RIP: 0010:truncate_folio_batch_exceptionals+0xff/0x260
[ 5.267076] Code: 00 00 41 39 df 7f 11 eb 78 83 c3 01 49 83 c4 08 41 39 df 74 6c 48 63 f3 48 83 fe 1f 0f 83 3c 01 00 00 43 f6 44 26 08 01 74 df <0f> 0b 4a 8b 34 22 4c 89 ef 48 89 55 90 e8 ff 54 1f 00 48 8b 55 90
[ 5.267083] RSP: 0018:ffffc900013f36c8 EFLAGS: 00010202
[ 5.267095] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 5.267101] RDX: ffffc900013f3790 RSI: 0000000000000000 RDI: ffff8882a1407898
[ 5.267108] RBP: ffffc900013f3740 R08: 0000000000000000 R09: 0000000000000000
[ 5.267113] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[ 5.267119…

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

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-2025-39868 has been found in Kernel.
Successful exploitation can lead to full system takeover.
What to do: upgrade Kernel to 6.16.8 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-39868" on the vendor's site.

CVE-2025-39868 (Kernel)
Attack vector: local / no user interaction
Patched: 6.16.8 — 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: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 6.16.8.

🛡️ 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
Identify exposure identify
```
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
Apply patch patch
```
Upgrade Kernel to 6.16.8
```
ステージング環境で 6.16.8 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
Post-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。

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"6.15.0"},{"fixed":"6.16.8"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-39868 linux-lts Fixed in: 6.18.35-r1
Debian DEBIAN-CVE-2025-39868 linux Fixed in: 6.16.8-1
Ubuntu UBUNTU-CVE-2025-39868 linux-hwe-edge