CVE-2026-53013 macvlan: fix macvlan_get_size() not reserving space for IFLA_MACVLAN_BC_CUTOFF
A missing size calculation in the Linux kernel macvlan driver causes netlink dump failures, preventing interface status retrieval when broadcast cutoff is configured.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53013?
CVE-2026-53013 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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") fixed the missing nla_policy entry but still did not fix the size calculation.
Which versions are affected by CVE-2026-53013?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53013?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53013 being exploited?
There is no known exploitation of CVE-2026-53013 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53013, DEBIAN-CVE-2026-53013, GHSA-mh75-v23p-mcvc, ROOT-OS-UBUNTU-2404-CVE-2026-53013, UBUNTU-CVE-2026-53013.