Vulnerability in Kernel (CVE-2025-39874)

Summary

Vulnerability in Kernel (CVE-2025-39874). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.16.8 or later.

Original description

The description as published by the source.

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

macsec: sync features on RTM_NEWLINK

Syzkaller managed to lock the lower device via ETHTOOL_SFEATURES:

netdev_lock include/linux/netdevice.h:2761 [inline]
netdev_lock_ops include/net/netdev_lock.h:42 [inline]
netdev_sync_lower_features net/core/dev.c:10649 [inline]
__netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819
netdev_update_features+0x6d/0xe0 net/core/dev.c:10876
macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533
notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
call_netdevice_notifiers net/core/dev.c:2281 [inline]
netdev_features_change+0x85/0xc0 net/core/dev.c:1570
__dev_ethtool net/ethtool/ioctl.c:3469 [inline]
dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502
dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759

It happens because lower features are out of sync with the upper:

__dev_ethtool (real_dev)
netdev_lock_ops(real_dev)
ETHTOOL_SFEATURES
__netdev_features_change
netdev_sync_upper_features
disable LRO on the lower
if (old_features != dev->features)
netdev_features_change
fires NETDEV_FEAT_CHANGE
macsec_notify
NETDEV_FEAT_CHANGE
netdev_update_features (for each macsec dev)
netdev_sync_lower_features
if (upper_features != lower_features)
netdev_lock_ops(lower) # lower == real_dev
stuck
...

netdev_unlock_ops(real_…

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-2025-39874 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.16.8 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-39874" on the vendor's site.

CVE-2025-39874 (Kernel)
Attack vector: local / no user interaction
Patched: 6.16.8 — 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 6.16.8.

🛡️ 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 6.16.8
```
ステージング環境で 6.16.8 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":"6.15.0"},{"fixed":"6.16.8"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-39874 linux-lts Fixed in: 6.18.35-r1
Debian DEBIAN-CVE-2025-39874 linux Fixed in: 6.16.8-1
Ubuntu UBUNTU-CVE-2025-39874 linux-hwe-edge