Description
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.
References6
- git.kernel.org/stable/c/54292b167466cdf42176b7b6f01da66c184deb12
- git.kernel.org/stable/c/9075efb9b2c1d9d7a8285c937b64aa93ca0c41b7
- git.kernel.org/stable/c/cee6688e5731c0591643521716d1a1a5c1a98bf8
- git.kernel.org/stable/c/d59d3b19e1cd1a01a6db59705327387a30aed153
- git.kernel.org/stable/c/ecf69d4b43370c587e48d4d70289dbdb7e039d4d
- git.kernel.org/stable/c/f49ed02fd8c98da823fdd7b00d64a8cc1d1883ac
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 3 · as of 11 November 2026
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.