CVE-2026-23001

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

macvlan: fix possible UAF in macvlan_forward_source()

Add RCU protection on (struct macvlan_source_entry)->vlan.

Whenever macvlan_hash_del_source() is called, we must clear entry->vlan pointer before RCU grace period starts.

This allows macvlan_forward_source() to skip over entries queued for freeing.

Note that macvlan_dev are already RCU protected, as they are embedded in a standard netdev (netdev_priv(ndev)).

https: //lore.kernel.org/netdev/[email protected]/T/#u

A use-after-free can occur in macvlan source-mode forwarding when a source hash entry is deleted while the transmit/forwarding path still dereferences entry.vlan without proper RCU protection. A local attacker who can configure macvlan networking can race deletion with packet processing to crash the kernel and potentially achieve memory corruption. Exploitation typically requires the CAP_NET_ADMIN capability (often within a user namespace).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent module macvlan from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.