CVE-2026-53013

/// Technical description

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

macvlan: fix macvlan_get_size() not reserving space for IFLA_MACVLAN_BC_CUTOFF

macvlan_get_size() does not account for IFLA_MACVLAN_BC_CUTOFF, but

macvlan_fill_info() conditionally includes it when port->bc_cutoff != 1.

This causes nla_put_s32() to fail with -EMSGSIZE when the netlink skb

runs out of space, triggering a WARN_ON in rtnetlink and preventing the

interface from being dumped.

The bug can be reproduced with:

ip link add macvlan0 link eth0 type macvlan mode bridge

ip link set macvlan0 type macvlan bc_cutoff 0

ip -d link show macvlan0 # fails with -EMSGSIZE

The bc_cutoff feature was added in commit 954d1fa1ac93 ("macvlan: Add

netlink attribute for broadcast cutoff"), which added the nla_put_s32()

call in macvlan_fill_info() but missed adding the corresponding

nla_total_size(4) in macvlan_get_size(). A follow-up commit

55cef78c244d ("macvlan: add forgotten nla_policy for

IFLA_MACVLAN_BC_CUTOFF") fi

/// 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