CVE-2026-68204 media: vivid: check for vb2_is_busy() when toggling caps
A race condition in the Linux kernel vivid driver allows unexpected format changes during buffer setup, potentially causing system instability or crashes.
- 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-2026-68204?
CVE-2026-68204 is a high-severity vulnerability in Linux, published on 10 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:
media: vivid: check for vb2_is_busy() when toggling caps
The vivid_update_format_cap/out() functions must only be called if the capture/output queue are not busy. But for the controls that select the CROP/COMPOSE/SCALE capability that is not checked.
Only when streaming starts will they be set to 'grabbed' and it is impossible to change the control, but between REQBUFS and STREAMON you are still allowed to set these controls. Since vivid_update_format_cap/out will change the format, this can cause unexpected results.
Besides adding these checks, also add a WARN_ON in vivid_update_format_cap/out() if the queue is busy.
I'm 90% certain that this is the cause of this syzbot bug:
https://syzkaller.appspot.com/bug?extid=dac8f5eaa46837e97b89
But since we never have reproducers, it is hard to be certain. In any case, these checks are needed regardless.
Which versions are affected by CVE-2026-68204?
How do I fix CVE-2026-68204?
Apply the vendor's patch.
Is CVE-2026-68204 being exploited?
There is no known exploitation of CVE-2026-68204 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68204, DEBIAN-CVE-2026-68204, GHSA-5xgr-hpwf-wcm3, UBUNTU-CVE-2026-68204.