CVE-2026-72405
Received Received - Intake

Double Queueing Vulnerability in Linux Kernel UDP Tunnel

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

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.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-72405
EUVD
EUVD-2026-59304

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's UDP tunnel functionality. It occurs when a workqueue operation is incorrectly handled, leading to a structure being freed while a related work item is still active. The issue arises from a race condition where a work item is queued multiple times, causing the kernel to mistakenly free a structure that is still in use.

Detection Guidance

This vulnerability is specific to the Linux kernel's UDP tunnel implementation and may not have direct detection commands. Monitor kernel logs for warnings related to udp_tunnel_nic_device_sync_work or debugobjects issues. Check for use-after-free errors in system logs or kernel crash dumps.

Impact Analysis

This vulnerability could lead to system crashes, data corruption, or privilege escalation if exploited. Systems running vulnerable Linux kernel versions with UDP tunnel functionality enabled may be affected. Attackers could potentially trigger the use-after-free condition to execute arbitrary code or cause denial-of-service.

Mitigation Strategies

Apply the latest kernel patches or updates that include the fix for this issue. If immediate patching is not possible, avoid concurrent device operations that could trigger the race condition. Monitor system stability and kernel logs for signs of exploitation or crashes.

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