Summary

Vulnerability in Kernel (CVE-2025-40119). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.17.3 or later.

Original description

The description as published by the source.

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

ext4: fix potential null deref in ext4_mb_init()

In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called
when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo
slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy()
lacks null pointer checking, this leads to a null pointer dereference.

==================================================================
EXT4-fs: no memory for groupinfo slab cache
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 0 P4D 0
Oops: Oops: 0002 [#1] SMP PTI
CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none)
RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40
Call Trace:

xa_destroy+0x61/0x130
ext4_mb_init+0x483/0x540
__ext4_fill_super+0x116d/0x17b0
ext4_fill_super+0xd3/0x280
get_tree_bdev_flags+0x132/0x1d0
vfs_get_tree+0x29/0xd0
do_new_mount+0x197/0x300
__x64_sys_mount+0x116/0x150
do_syscall_64+0x50/0x1c0
entry_SYSCALL_64_after_hwframe+0x76/0x7e

Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy()
to prevent this issue. The same fix is also applied to
ext4_mb_largest_free_orders_destroy().

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-2025-40119 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.17.3 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-40119" on the vendor's site.

CVE-2025-40119 (Kernel)
Patched: 6.17.3 — 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 6.17.3.

🛡️ 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 6.17.3
```
ステージング環境で 6.17.3 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":"6.17.0"},{"fixed":"6.17.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-40119 linux-lts Fixed in: 6.18.35-r1
Ubuntu UBUNTU-CVE-2025-40119 linux-hwe-edge