CVE-2026-89891: Linux Vulnerability

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.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < f61720346fdcc1a2deec59a2f6cbb0cc20d1dc18; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 1ed575b1991f68569eb589b7747d3bc26aa6a8a2; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < da4b07da6281e39ce4c01e1227e036f3bf600e14; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 20aacd87550be297dc39a3f9532dcfff91586510; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 20c2c65f3d9f7c278dc9750531d3201ac8bf78b7; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 0782807552b6aff41b4656c6c9076a3231d3e79d; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 16cb1ee17e093175b4d9ae33202f68e5b108cca2; >= f410b4093fdd4d8f4644d3d486afe3040eceef7b, < 826915b6b65e2d3251e7248ea54289a22d748c84
Linux	Linux	4.17

References

Timeline

Published: Sep 16, 2026
Last Modified: Sep 16, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89891?

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.

How severe is CVE-2026-89891?

Severity scoring for CVE-2026-89891 is pending analysis.

How do I fix CVE-2026-89891?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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