CVE-2026-63988

/// Technical description

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

bridge: Fix sleep in atomic context in sysfs path

Since the start of the git history, brport_store() always acquired the

bridge lock. Back then this decision made sense: The bridge lock

protects the STP state of the bridge and its ports and at that time the

function was only used by two STP related attributes (cost and

priority).

Nowadays, brport_store() processes a lot more attributes and most of

them do not need the bridge lock:

* Bridge flags: Only require RTNL. Read locklessly by the data path.

Annotations can be added in net-next.

* FDB port flushing: Only requires the FDB lock.

* Multicast attributes: Only require the multicast lock.

* Group forward mask: Only requires RTNL. Read locklessly by the data

path. Annotations can be added in net-next.

* Backup port: Only requires RTNL. Read locklessly by the data path.

This is a problem as the bridge calls dev_set_promiscuity() when certain

bridge port fla

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References