Vulnerability in Kernel (CVE-2025-21675)

Summary

Vulnerability in Kernel (CVE-2025-21675). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.1.127, 6.6.74, 6.12.11 or later.

Original description

The description as published by the source.

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

net/mlx5: Clear port select structure when fail to create

Clear the port select structure on error so no stale values left after
definers are destroyed. That's because the mlx5_lag_destroy_definers()
always try to destroy all lag definers in the tt_map, so in the flow
below lag definers get double-destroyed and cause kernel crash:

mlx5_lag_port_sel_create()
mlx5_lag_create_definers()
mlx5_lag_create_definer() <- Failed on tt 1
mlx5_lag_destroy_definers() <- definers[tt=0] gets destroyed
mlx5_lag_port_sel_create()
mlx5_lag_create_definers()
mlx5_lag_create_definer() <- Failed on tt 0
mlx5_lag_destroy_definers() <- definers[tt=0] gets double-destroyed

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 64k pages, 48-bit VAs, pgdp=0000000112ce2e00
[0000000000000008] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in: iptable_raw bonding ip_gre ip6_gre gre ip6_tunnel tunnel6 geneve ip6_udp_tunnel udp_tu…

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-2025-21675 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.1.127, 6.6.74, 6.12.11 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-21675" on the vendor's site.

CVE-2025-21675 (Kernel)
Attack vector: local / no user interaction
Patched: 6.1.127, 6.6.74, 6.12.11 — 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 6.1.127, 6.6.74, 6.12.11.

🛡️ 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 6.1.127, 6.6.74, 6.12.11
```
ステージング環境で 6.1.127, 6.6.74, 6.12.11 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":"5.16.0"},{"fixed":"6.1.127"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.74"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.11"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-21675 linux-lts Fixed in: 6.1.127-r0
Debian DEBIAN-CVE-2025-21675 linux Fixed in: 6.1.128-1
Ubuntu UBUNTU-CVE-2025-21675 linux-hwe-edge