CVE-2025-39925
can: j1939: implement NETDEV_UNREGISTER notification handler
Description
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]
INFO
Published Date :
Oct. 1, 2025, 8:15 a.m.
Last Modified :
Sept. 2, 2026, 1:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Apply the kernel patch for the j1939 protocol.
- Ensure device unregistration completes correctly.
- Update the Linux kernel to the patched version.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-39925.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-39925 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-39925
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-39925 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-39925 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 02, 2026
Action Type Old Value New Value Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/39xxx/CVE-2025-39925.json">CVE-2025-39925</a> Added Reference https://git.kernel.org/stable/c/2c88069fac2c792e228e6a4ae71c9b9b5b9a87a6 Added Reference https://git.kernel.org/stable/c/479d8a2aedcc1db16f14c1a8a9c74b5bdf18b9ac Added Reference https://git.kernel.org/stable/c/4e154cb5e7681c2910e2dfa09f05e3469e333745 Added Reference https://git.kernel.org/stable/c/76957b618ce729c3bd1e782fbc9d9991af653925 Added Reference https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a Added Reference https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262 Removed Reference https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a Removed Reference https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262 Removed Reference Type https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a Types: Patch Removed Reference Type https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262 Types: Patch -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '9d71dd0c70099914fcd063135da3c580865e924c', 'lessThan': 'da9e8f429139928570407e8f90559b5d46c20262', 'versionType': 'git'}, {'status': 'affected', 'version': '9d71dd0c70099914fcd063135da3c580865e924c', 'lessThan': '7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a', 'versionType': 'git'}], 'programFiles': ['net/can/j1939/j1939-priv.h', 'net/can/j1939/main.c', 'net/can/j1939/socket.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.16.8', 'versionType': 'semver', 'lessThanOrEqual': '6.16.*'}, {'status': 'unaffected', 'version': '6.17', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/can/j1939/j1939-priv.h', 'net/can/j1939/main.c', 'net/can/j1939/socket.c'], 'defaultStatus': 'affected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2025-39925', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-01-14T17:39:05.628974Z'} -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jan. 14, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H -
Initial Analysis by [email protected]
Dec. 11, 2025
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.4 up to (excluding) 6.16.8 Added Reference Type kernel.org: https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262 Types: Patch -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Oct. 01, 2025
Action Type Old Value New Value Added Description 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] Added Reference https://git.kernel.org/stable/c/7fcbe5b2c6a4b5407bf2241fdb71e0a390f6ab9a Added Reference https://git.kernel.org/stable/c/da9e8f429139928570407e8f90559b5d46c20262