CVE-2026-89891 media: em28xx: fix use-after-free of dev_next->devlist on disconnect
A use-after-free in the em28xx media driver allows local attackers to cause kernel crashes or potentially execute code via USB device disconnection.
- 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-2026-89891?
CVE-2026-89891 is an use after free vulnerability in Linux, published on 16 Sep 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: em28xx: fix use-after-free of dev_next->devlist on disconnect
When a device with has_dual_ts=1 is probed and the is_audio_only path is taken, both dev and dev->dev_next are added to the global em28xx_devlist via em28xx_init_extension(). However, during disconnect, em28xx_close_extension(dev) only calls list_del(&dev->devlist), leaving dev->dev_next->devlist still linked in the global list. When dev_next is subsequently freed via kref_put(), its devlist entry becomes a dangling pointer in em28xx_devlist. The next device probe that calls em28xx_init_extension() triggers a list corruption BUG when list_add_tail detects the freed node.
This bug was exposed by commit a368ecde8a50 ("USB: core: Fix duplicate endpoint bug by clearing reserved bits in the descriptor") which clears reserved bits in bEndpointAddress during endpoint parsing. This causes fuzzed endpoint addresses like 0xf3 to be normalized to 0x83, which em28xx interprets as a vendor audio endpoint, enabling the is_audio_only + has_dual_ts code path that was previously unreachable with such descriptors.
Fix this by removing dev->dev_next->devlist from the global list in em28xx_close_extension() before the device is freed.
Which versions are affected by CVE-2026-89891?
How do I fix CVE-2026-89891?
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-2026-89891 being exploited?
There is no known exploitation of CVE-2026-89891 in the wild and no public exploit code.
Sources
Also known as AZL-101504, BELL-CVE-2026-89891, DEBIAN-CVE-2026-89891, GHSA-5cx6-377w-hc5f, UBUNTU-CVE-2026-89891.