CVE-2026-89951

/// Technical description

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

batman-adv: fix stale receive device on merged fragments

Fragment reassembly reuses the skb from the highest-numbered buffered

fragment as the merged packet. When that fragment was received on a hard

interface which is deleted before the chain completes, the merged skb can

re-enter the receive path with a stale skb->dev and skb_iif.

batadv_batman_skb_recv() passes such merged packets through the normal

receive handlers again. DAT and bridge loop avoidance both derive the ARP

header length from skb->dev, so they can dereference the freed net_device

before the packet reaches the local mesh interface.

Refresh the receive device metadata from the current receive device before

running the packet handlers. This keeps internally reinjected merged

fragments consistent with the normal receive path after hard interface

teardown.

/// 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