CVE-2023-53641 wifi: ath9k: hif_usb: fix memory leak of remain_skbs
A memory leak in the ath9k USB WiFi driver allows attackers to cause a denial of service by triggering device deinitialization or suspend states.
- 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-2023-53641?
CVE-2023-53641 is a medium-severity denial of service vulnerability in Linux kernel, published on 7 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:
wifi: ath9k: hif_usb: fix memory leak of remain_skbs
hif_dev->remain_skb is allocated and used exclusively in ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is processed and subsequently freed (in error paths) only during the next call of ath9k_hif_usb_rx_stream().
So, if the urbs are deallocated between those two calls due to the device deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream() is not called next time and the allocated remain_skb is leaked. Our local Syzkaller instance was able to trigger that.
remain_skb makes sense when receiving two consecutive urbs which are logically linked together, i.e. a specific data field from the first skb indicates a cached skb to be allocated, memcpy'd with some data and subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs deallocation supposedly makes that link irrelevant so we need to free the cached skb in those cases.
Fix the leak by introducing a function to explicitly free remain_skb (if it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL when it has not been allocated at all (hif_dev struct is kzalloced) or when it has been processed in next call to ath9k_hif_usb_rx_stream().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Weakness: CWE-401
Which versions are affected by CVE-2023-53641?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-53641?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-53641 being exploited?
There is no known exploitation of CVE-2023-53641 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2023-53641, DEBIAN-CVE-2023-53641, GHSA-hh9m-7vg3-wpg4, UBUNTU-CVE-2023-53641.