Medium [CVE-2026-68301] fix memory leak on slave unregistration by removing synced VLANs
This medium-severity Red Hat Linux advisory covers CVE-2026-68301 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
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.
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.
A flaw was found in the Linux kernel's High-availability Seamless Redundancy (HSR) networking module. When an HSR slave device is unregistered, the system fails to properly remove synced Virtual Local Area Networks (VLANs).
This oversight causes the slave device to retain a reference count on these VLANs, leading to a memory leak. A local attacker could potentially exploit this to cause resource exhaustion.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 days ago·verify at source
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