CVE-2026-68301

Received Received - Intake

Memory Leak in Linux Kernel HSR Slave Unregistration

Publication date: 2026-08-10

Last updated on: 2026-08-19

Assigner: kernel.org

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-10

Last Modified

2026-08-19

Generated

2026-08-30

AI Q&A

2026-08-10

EPSS Evaluated

2026-08-29

NVD

CVE-2026-68301

EUVD

EUVD-2026-55402

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is a memory leak in the Linux kernel's HSR (High-availability Seamless Redundancy) implementation. When a slave device is unregistered while HSR is active, the system fails to remove synced VLAN IDs from the slave, causing the VLAN structures to remain allocated even after the slave is destroyed.

Detection Guidance

This vulnerability is specific to the Linux kernel's HSR (High-availability Seamless Redundancy) implementation. Detection requires checking for memory leaks in VLAN handling during HSR slave unregistration. Monitor kernel logs for memory allocation errors or use tools like 'slabtop' or 'vmstat' to track memory usage. No direct commands are provided in the context to detect this issue.

Impact Analysis

This vulnerability can lead to gradual memory exhaustion on systems using HSR, potentially causing performance degradation or system crashes due to running out of memory. It primarily affects systems with active HSR configurations and dynamic network interface changes.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it is a memory leak issue in the Linux kernel's HSR networking feature. It may indirectly impact system stability or availability, which could affect data processing or storage operations subject to these regulations.

Mitigation Strategies

Apply the kernel patch that resolves this issue by updating to a version where the fix is included. The patch ensures VLAN IDs are properly cleaned up when HSR slave devices are unregistered. Monitor kernel updates from your Linux distribution for the patched version.

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