Vulnerability in Kernel (CVE-2025-40237)

Summary

Vulnerability in Kernel (CVE-2025-40237). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.6.73, 6.6.115, 6.12.56, 6.17.6 or later.

Original description

The description as published by the source.

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

fs/notify: call exportfs_encode_fid with s_umount

Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while
the overlayfs is being unmounted, can lead to dereferencing NULL ptr.

This issue was found by syzkaller.

Race Condition Diagram:

Thread 1 Thread 2

generic_shutdown_super()
shrink_dcache_for_umount
sb->s_root = NULL

                |
                |             vfs_read()
                |              inotify_fdinfo()
                |               * inode get from mark *
                |               show_mark_fhandle(m, inode)
                |                exportfs_encode_fid(inode, ..)
                |                 ovl_encode_fh(inode, ..)
                |                  ovl_check_encode_origin(inode)
                |                   * deref i_sb->s_root *
                |
                |
                v

fsnotify_sb_delete(sb)

Which then leads to:

[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)

[ 32.143353] Call Trace:
[ 32.143732] ovl_encode_fh+0xd5/…

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-2025-40237 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.6.73, 6.6.115, 6.12.56, 6.17.6 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-40237" on the vendor's site.

CVE-2025-40237 (Kernel)
Patched: 6.6.73, 6.6.115, 6.12.56, 6.17.6 — 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: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 6.6.73, 6.6.115, 6.12.56, 6.17.6.

🛡️ 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 6.6.73, 6.6.115, 6.12.56, 6.17.6
```
ステージング環境で 6.6.73, 6.6.115, 6.12.56, 6.17.6 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":"0"},{"fixed":"6.6.73"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.6.115"},{"fixed":"6.12.56"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.17.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-40237 linux-lts Fixed in: 6.18.35-r1
Debian DEBIAN-CVE-2025-40237 linux Fixed in: 6.12.57-1
Ubuntu UBUNTU-CVE-2025-40237 linux