CVE-2026-31509 nfc: nci: fix circular locking dependency in nci_close_device
A circular locking dependency in the Linux kernel NFC driver can cause a deadlock, leading to a denial of service.
- 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-2026-31509?
CVE-2026-31509 is a medium-severity vulnerability in Linux kernel, published on 22 Apr 2026. 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:
nfc: nci: fix circular locking dependency in nci_close_device
nci_close_device() flushes rx_wq and tx_wq while holding req_lock. This causes a circular locking dependency because nci_rx_work() running on rx_wq can end up taking req_lock too:
nci_rx_work -> nci_rx_data_packet -> nci_data_exchange_complete -> __sk_destruct -> rawsock_destruct -> nfc_deactivate_target -> nci_deactivate_target -> nci_request -> mutex_lock(&ndev->req_lock)
Move the flush of rx_wq after req_lock has been released. This should safe (I think) because NCI_UP has already been cleared and the transport is closed, so the work will see it and return -ENETDOWN.
NIPA has been hitting this running the nci selftest with a debug kernel on roughly 4% of the runs.
Weakness: CWE-667
Which versions are affected by CVE-2026-31509?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31509?
Apply the vendor's patch.
Is CVE-2026-31509 being exploited?
There is no known exploitation of CVE-2026-31509 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83336, BELL-CVE-2026-31509, DEBIAN-CVE-2026-31509, GHSA-x33w-8476-hwm3, ROOT-OS-DEBIAN-11-CVE-2026-31509, ROOT-OS-DEBIAN-12-CVE-2026-31509 and 3 more.