CVE-2023-53608 nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()
A race condition in the nilfs2 filesystem can lead to a use-after-free, potentially allowing local attackers to execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-53608?
CVE-2023-53608 is a high-severity use after free vulnerability in Linux kernel, published on 4 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()
The finalization of nilfs_segctor_thread() can race with nilfs_segctor_kill_thread() which terminates that thread, potentially causing a use-after-free BUG as KASAN detected.
At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member of "struct nilfs_sc_info" to indicate the thread has finished, and then notifies nilfs_segctor_kill_thread() of this using waitqueue "sc_wait_task" on the struct nilfs_sc_info.
However, here, immediately after the NULL assignment to "sc_task", it is possible that nilfs_segctor_kill_thread() will detect it and return to continue the deallocation, freeing the nilfs_sc_info structure before the thread does the notification.
This fixes the issue by protecting the NULL assignment to "sc_task" and its notification, with spinlock "sc_state_lock" of the struct nilfs_sc_info. Since nilfs_segctor_kill_thread() does a final check to see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate the race.
Weakness: CWE-416
Which versions are affected by CVE-2023-53608?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53608?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2023-53608 being exploited?
There is no known exploitation of CVE-2023-53608 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53608, DEBIAN-CVE-2023-53608, GHSA-g3qq-fg79-63v4, UBUNTU-CVE-2023-53608.