net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync
CVE-2026-72405 · published 15 Aug 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-72405?
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Who is affected
- Linux Linux: cc4e3835eff474aa274d6e1d18f69d9d296d3b76 to < f49ed02fd8c98da823fdd7b00d64a8cc1d1883ac, cc4e3835eff474aa274d6e1d18f69d9d296d3b76 to < cee6688e5731c0591643521716d1a1a5c1a98bf8, cc4e3835eff474aa274d6e1d18f69d9d296d3b76 to < 9075efb9b2c1d9d7a8285c937b64aa93ca0c41b7, cc4e3835eff474aa274d6e1d18f69d9d296d3b76 to < 54292b167466cdf42176b7b6f01da66c184deb12
- Linux Linux: 5.9
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync
Yue Sun reported a use-after-free and debugobjects warning in
udp_tunnel_nic_device_sync_work() during concurrent device operations.
The workqueue core clears the internal pending bit before invoking the
worker. At that point, a concurrent thread can queue the work again.
When the already running worker eventually clears the work_pending flag
to 0, it mistakenly clears the flag for the newly queued instance.
udp_tunnel_nic_unregister() then observes work_pending as 0 and frees
the structure while the second work item is still active in the queue,
leading to UAF.
Fix this by returning early in udp_tunnel_nic_device_sync() if
work_pending is already set, preventing redundant work queueing.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/f49ed02fd8c98da823fdd7b00d64a8cc1d1883ac
- git.kernel.org/stable/c/cee6688e5731c0591643521716d1a1a5c1a98bf8
- git.kernel.org/stable/c/9075efb9b2c1d9d7a8285c937b64aa93ca0c41b7
- git.kernel.org/stable/c/54292b167466cdf42176b7b6f01da66c184deb12
- git.kernel.org/stable/c/ecf69d4b43370c587e48d4d70289dbdb7e039d4d
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON