CVE-2026-68301 net: hsr: fix memory leak on slave unregistration by removing synced VLANs
A memory leak in the Linux kernel HSR driver allows local attackers to cause denial of service by triggering slave device unregistration.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68301?
CVE-2026-68301 is a memory corruption vulnerability in Linux, published on 10 Aug 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:
net: hsr: fix memory leak on slave unregistration by removing synced VLANs
When an HSR master device is brought UP, it auto-adds VLAN 0 via vlan_vid0_add(), which propagates VID 0 to its slave devices (slave A and B).
If a slave device is later unregistered while HSR is active (e.g., during netns cleanup or interface destruction), hsr_del_port() is called to detach the slave port from the HSR master. However, hsr_del_port() currently does not delete the VLAN IDs that were synced to the slave device by HSR.
As a result, the slave device retains a refcount on VID 0 (and any other synced VLANs). When the slave device is destroyed, its vlan_info / vlan_vid_info structure remains allocated, leading to a memory leak.
Fix this by calling vlan_vids_del_by_dev(port->dev, master->dev) in hsr_del_port() before unlinking slave A or slave B ports, matching the propagation logic in hsr_ndo_vlan_rx_add_vid() / hsr_ndo_vlan_rx_kill_vid() and the cleanup behavior in bonding and team drivers.
Which versions are affected by CVE-2026-68301?
How do I fix CVE-2026-68301?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-68301 being exploited?
There is no known exploitation of CVE-2026-68301 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68301, DEBIAN-CVE-2026-68301, GHSA-f9h5-hhgx-wh5m, UBUNTU-CVE-2026-68301.