Vulnerability in Kernel (CVE-2025-39996)

Summary

Vulnerability in Kernel (CVE-2025-39996). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1 or later.

Original description

The description as published by the source.

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

media: b2c2: Fix use-after-free causing by irq_check_work in flexcop_pci_remove

The original code uses cancel_delayed_work() in flexcop_pci_remove(), which
does not guarantee that the delayed work item irq_check_work has fully
completed if it was already running. This leads to use-after-free scenarios
where flexcop_pci_remove() may free the flexcop_device while irq_check_work
is still active and attempts to dereference the device.

A typical race condition is illustrated below:

This is confirmed by a KASAN report:

==================================================================
BUG: KASAN: slab-use-after-free in __run_timer_base.part.0+0x7d7/0x8c0
Write of size 8 at addr ffff8880093aa8c8 by task bash/135
...
Call Trace:

dump_stack_lvl+0x55/0x70
print_report+0xcf/0x610
? __run_timer_base.part.0+0x7d7/0x8c0
kasan_report+0xb8/0xf0
? __run_timer_base.part.0+0x7d7/0x8c0
__run_timer_base.part.0+0x7d7/0x8c0
? __pfx___run_timer_base.part.0+0x10/0x10
? __pfx_read_tsc+0x10/0x10
? ktime_get+0x60/0x140
? lapic_next_event+0x11/0x20
? clockevents_program_event+0x1d4/0x2a0
run_timer_softirq+0xd1/0x190
handle_softi…

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-2025-39996 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-39996" on the vendor's site.

CVE-2025-39996 (Kernel)
Patched: 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1 — 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 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1.

🛡️ 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 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1
```
ステージング環境で 5.4.301, 5.10.246, 5.15.195, 6.1.156, 6.6.110, 6.12.51, 6.16.11, 6.17.1 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":"2.6.29"},{"fixed":"5.4.301"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.246"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.195"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.156"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.16.11"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.17.0"},{"fixed":"6.17.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-39996 linux-lts Fixed in: 6.1.156-r0
Debian DEBIAN-CVE-2025-39996 linux Fixed in: 5.10.247-1
Ubuntu UBUNTU-CVE-2025-39996 linux