CVE-2025-40002
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-18

Last updated on: 2025-10-21

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Fix use-after-free in tb_dp_dprx_work The original code relies on cancel_delayed_work() in tb_dp_dprx_stop(), which does not ensure that the delayed work item tunnel->dprx_work has fully completed if it was already running. This leads to use-after-free scenarios where tb_tunnel is deallocated by tb_tunnel_put(), while tunnel->dprx_work remains active and attempts to dereference tb_tunnel in tb_dp_dprx_work(). A typical race condition is illustrated below: CPU 0 | CPU 1 tb_dp_tunnel_active() | tb_deactivate_and_free_tunnel()| tb_dp_dprx_start() tb_tunnel_deactivate() | queue_delayed_work() tb_dp_activate() | tb_dp_dprx_stop() | tb_dp_dprx_work() //delayed worker cancel_delayed_work() | tb_tunnel_put(tunnel); | | tunnel = container_of(...); //UAF | tunnel-> //UAF Replacing cancel_delayed_work() with cancel_delayed_work_sync() is not feasible as it would introduce a deadlock: both tb_dp_dprx_work() and the cleanup path acquire tb->lock, and cancel_delayed_work_sync() would wait indefinitely for the work item that cannot proceed. Instead, implement proper reference counting: - If cancel_delayed_work() returns true (work is pending), we release the reference in the stop function. - If it returns false (work is executing or already completed), the reference is released in delayed work function itself. This ensures the tb_tunnel remains valid during work item execution while preventing memory leaks. This bug was found by static analysis.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2025-10-18
Last Modified
2025-10-21
Generated
2026-05-07
AI Q&A
2025-10-18
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40002
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a use-after-free bug in the Linux kernel's Thunderbolt driver. It occurs because the code uses cancel_delayed_work() to stop a delayed work item, but this function does not guarantee that the work has fully completed if it was already running. As a result, the tb_tunnel object can be deallocated while the delayed work still tries to access it, leading to a use-after-free scenario. The fix involves implementing proper reference counting to ensure the tb_tunnel remains valid during the work item's execution and prevent memory leaks.


How can this vulnerability impact me? :

This vulnerability can lead to use-after-free conditions in the Linux kernel, which may cause system instability, crashes, or potentially allow an attacker to execute arbitrary code or escalate privileges if they can trigger the race condition. It affects the reliability and security of systems using the affected Thunderbolt driver.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version where the use-after-free in tb_dp_dprx_work is fixed. The fix involves proper reference counting and changes in the handling of delayed work items in the thunderbolt driver, replacing cancel_delayed_work() usage with a mechanism that ensures the tb_tunnel remains valid during work item execution. Since the issue is in kernel code, applying the vendor's patch or upgrading to a fixed kernel version is the immediate step.


Ask Our AI Assistant
Need more information? Ask your question to get an AI reply (Powered by our expertise)
0/70
EPSS Chart