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CVE-2025-40297 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix use-after-free due to MST port state bypass syzbot reported[1] a use-after-free when deleting an expired fdb. It is due to a race condition between learning still happening and a port being deleted, after all its fdbs have been flushed. The port's state has been toggled to disabled so no learning should happen at that time, but if we have MST enabled, it will bypass the port's state, that together with VLAN filtering disabled can lead to fdb learning at a time when it shouldn't happen while the port is being deleted. VLAN filtering must be disabled because we flush the port VLANs when it's being deleted which will stop learning. This fix adds a check for the port's vlan group which is initialized to NULL when the port is getting deleted, that avoids the port state bypass. When MST is enabled there would be a minimal new overhead in the fast-path because the port's vlan group pointer is cache-hot. [1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/3b60ce334c1ce8b3fad7e02dcd5ed9f6646477c8 kernel.org
https://git.kernel.org/stable/c/8dca36978aa80bab9d4da130c211db75c9e00048 kernel.org
https://git.kernel.org/stable/c/991fbe1680cd41a5f97c92cd3a3496315df36e4b kernel.org
https://git.kernel.org/stable/c/bf3843183bc3158e5821b46f330c438ae9bd6ddb kernel.org
https://git.kernel.org/stable/c/e19085b2a86addccff33ab8536fc67ebd9d52198 kernel.org

Weakness Enumeration

CWE-ID CWE Name Source

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-40297
NVD Published Date:
12/07/2025
NVD Last Modified:
12/07/2025
Source:
kernel.org