---
cve: "CVE-2025-39925"
severity: "MEDIUM"
cvss: 5.5
epss: "12%"
vendor: "Linux"
kev: false
exploited: false
published: "2025-10-01 08:15:35"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-16T04:44:20+02:00"
---

# CVE-2025-39925

> 5.5 MEDIUM

## Beschreibung

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

can: j1939: implement NETDEV_UNREGISTER notification handler

syzbot is reporting

  unregister_netdevice: waiting for vcan0 to become free. Usage count = 2

problem, for j1939 protocol did not have NETDEV_UNREGISTER notification
handler for undoing changes made by j1939_sk_bind().

Commit 25fe97cb7620 ("can: j1939: move j1939_priv_put() into sk_destruct
callback") expects that a call to j1939_priv_put() can be unconditionally
delayed until j1939_sk_sock_destruct() is called. But we need to call
j1939_priv_put() against an extra ref held by j1939_sk_bind() call
(as a part of undoing changes made by j1939_sk_bind()) as soon as
NETDEV_UNREGISTER notification fires (i.e. before j1939_sk_sock_destruct()
is called via j1939_sk_release()). Otherwise, the extra ref on "struct
j1939_priv" held by j1939_sk_bind() call prevents "struct net_device" from
dropping the usage count to 1; making it impossible for
unregister_netdevice() to continue.

[mkl: remove space in front of label]

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.15.220
- Kernel ≥ 6.1.187
- Kernel ≥ 6.6.156
- Kernel ≥ 6.12.108
- Kernel ≥ 6.16.8

## Referenzen

- <https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262>
- <https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a>
- <https://git.kernel.org/stable/c/2c88069fac2c792e228e6a4ae71c9b9b5b9a87a6>
- <https://git.kernel.org/stable/c/479d8a2aedcc1db16f14c1a8a9c74b5bdf18b9ac>
- <https://git.kernel.org/stable/c/4e154cb5e7681c2910e2dfa09f05e3469e333745>
- <https://git.kernel.org/stable/c/76957b618ce729c3bd1e782fbc9d9991af653925>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-39925) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_