Vulnerability in Kernel (CVE-2025-40235)

Summary

Vulnerability in Kernel (CVE-2025-40235). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 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:

btrfs: directly free partially initialized fs_info in btrfs_check_leaked_roots()

If fs_info->super_copy or fs_info->super_for_commit allocated failed in
btrfs_get_tree_subvol(), then no need to call btrfs_free_fs_info().
Otherwise btrfs_check_leaked_roots() would access NULL pointer because
fs_info->allocated_roots had not been initialised.

syzkaller reported the following information:
------------[ cut here ]------------
BUG: unable to handle page fault for address: fffffffffffffbb0
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 64c9067 P4D 64c9067 PUD 64cb067 PMD 0
Oops: Oops: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 1402 Comm: syz.1.35 Not tainted 6.15.8 #4 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), (...)
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline]
RIP: 0010:refcount_read include/linux/refcount.h:170 [inline]
RIP: 0010:btrfs_check_leaked_roots+0x18f/0x2c0 fs/btrfs/disk-io.c:1230
[...]
Call Trace:

btrfs_free_fs_info+0x310/0x410 fs/btrfs/disk-io.c:1280
btrfs_get_tree_subvol+0x592/0x6b0 fs/btrfs/super.c:2029
btrfs_get_tree+0x63/0x80 fs/btrfs/super.c:2097
vfs_get_tree+0x98/0x320 fs/super.c:1759
do_new_mount+…

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-2025-40235 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.12.56, 6.17.6 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-40235" on the vendor's site.

CVE-2025-40235 (Kernel)
Patched: 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 6.12.56, 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 6.12.56, 6.17.6
```
ステージング環境で 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":"6.8.0"},{"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-2025-40235 linux-lts Fixed in: 6.12.57-r0
Debian DEBIAN-CVE-2025-40235 linux Fixed in: 6.12.57-1
Ubuntu UBUNTU-CVE-2025-40235 linux-hwe-edge