CVE-2026-80659 mmc: vub300: defer reset until cmd_mutex is unlocked
A recursive locking bug in the vub300 MMC driver causes a deadlock and system hang when a USB command times out, requiring local access to trigger.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80659?
CVE-2026-80659 is a vulnerability in Linux, published on 28 Aug 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:
mmc: vub300: defer reset until cmd_mutex is unlocked
vub300_cmndwork_thread() holds cmd_mutex while it sends a command and waits for the command response. If the response wait times out, __vub300_command_response() kills the command URBs and then synchronously resets the USB device through usb_reset_device().
That reset path re-enters the driver through vub300_pre_reset(), which also takes cmd_mutex. The worker therefore tries to acquire the same mutex recursively while it is still holding it from the command path.
This issue was found by our static analysis tool and then manually reviewed against the current tree.
The grounded PoC kept the real worker and timeout/reset carrier:
vub300_cmndwork_thread() __vub300_command_response() usb_lock_device_for_reset() usb_reset_device() vub300_pre_reset()
Lockdep reported the same-task recursive acquisition on cmd_mutex:
WARNING: possible recursive locking detected ... (&test_vub300.cmd_mutex) ... at: usb_reset_device... [vuln_msv] ... (&test_vub300.cmd_mutex) ... at: vub300_cmndwork_thread+0x12/0x20 [vuln_msv] Workqueue: vub300_cmd_wq vub300_cmndwork_thread [vuln_msv] *** DEADLOCK ***
Return a flag from __vub300_command_response() when the timeout path needs a device reset, then perform the reset after vub300_cmndwork_thread() has cleared the in-flight command state and dropped cmd_mutex. The reset is still attempted before mmc_request_done(), preserving the existing request completion ordering while avoiding the recursive lock.
Which versions are affected by CVE-2026-80659?
How do I fix CVE-2026-80659?
Apply the vendor's patch.
Is CVE-2026-80659 being exploited?
There is no known exploitation of CVE-2026-80659 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-80659, DEBIAN-CVE-2026-80659, GHSA-7xh8-9fpc-p64f, UBUNTU-CVE-2026-80659.