CVE-2025-68339

What it is

In the Linux kernel, the following vulnerability has been resolved: atm/fore200e: Fix possible data race in fore200e_open() Protect access to fore200e->available_cell_rate with rate_mtx lock in the error handling path of fore200e_open() to prevent a data race. The field fore200e->available_cell_rate is a shared resource used to track available bandwidth. It is concurrently accessed by fore200e_open(), fore200e_close(), and fore200e_change_qos(). In fore200e_open(), the lock rate_mtx is correctly held when subtracting vcc->qos.txtp.max_pcr from available_cell_rate to reserve bandwidth. However, if the subsequent call to fore200e_activate_vcin() fails, the function restores the reserved bandwidth by adding back to available_cell_rate without holding the lock. This introduces a race condition because available_cell_rate is a global device resource shared across all VCCs. If the error path in fore200e_open() executes concurrently with operations like fore200e_close() or fore200e_change_qos() on other VCCs, a read-modify-write race occurs. Specifically, the error path reads the rate without the lock. If another CPU acquires the lock and modifies the rate (e.g., releasing bandwidth in fore200e_close()) between this read and the subsequent write, the error path will overwrite the concurrent update with a stale value. This results in incorrect bandwidth accounting.

At a glance

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2025-12-23 14:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-19 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: not scored yet.
• Fix: none linked yet, which raises it.

Details

Published

2025-12-23 14:16 UTC

Last modified

2026-10-19 21:10 UTC

Exploit probability

0.2% · EPSS, next 30 days

Record status

Deferred

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