Vulnerability in Kernel (CVE-2025-37953)

Summary

Vulnerability in Kernel (CVE-2025-37953). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.1.139, 6.6.91, 6.12.29, 6.14.7 or later.

Original description

The description as published by the source.

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

sch_htb: make htb_deactivate() idempotent

Alan reported a NULL pointer dereference in htb_next_rb_node()
after we made htb_qlen_notify() idempotent.

It turns out in the following case it introduced some regression:

For htb_next_rb_node(), after calling the 1st htb_deactivate(), the
clprio[prio]->ptr could be already set to NULL, which means
htb_next_rb_node() is vulnerable here.

For htb_deactivate(), although we checked qlen before calling it, in
case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again
which triggers the warning inside.

To fix the issues here, we need to:

Make htb_deactivate() idempotent, that is, simply return if we
already call it before.
Make htb_next_rb_node() safe against ptr==NULL.

Many thanks to Alan for testing and for the reproducer.

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-2025-37953 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.1.139, 6.6.91, 6.12.29, 6.14.7 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-37953" on the vendor's site.

CVE-2025-37953 (Kernel)
Patched: 6.1.139, 6.6.91, 6.12.29, 6.14.7 — 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 6.1.139, 6.6.91, 6.12.29, 6.14.7.

🛡️ 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 6.1.139, 6.6.91, 6.12.29, 6.14.7
```
ステージング環境で 6.1.139, 6.6.91, 6.12.29, 6.14.7 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":"6.1.138"},{"fixed":"6.1.139"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.6.90"},{"fixed":"6.6.91"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.12.28"},{"fixed":"6.12.29"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.14.6"},{"fixed":"6.14.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-37953 linux-lts Fixed in: 6.1.140-r0
Debian DEBIAN-CVE-2025-37953 linux Fixed in: 6.1.140-1