CVE-2026-90373: wifi: mt76: mt7915: clear wcid mask under mutex after RCU pointer clear

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7915: clear wcid mask under mutex after RCU pointer clear mt7915_remove_interface() cleared the wcid mask bit with no lock held and before clearing the RCU wcid pointer. The mask is a non-atomic RMW shared with the allocators, which all run under dev->mt76.mutex; on DBDC the two wiphys share one mt76_dev, so this raced add_interface/sta_add on the other band and could leak or double-hand-out a wcid. Clearing the bit before the RCU pointer also let a concurrent allocation reuse the index and publish its wcid, which the subsequent NULL assignment then wiped. Move the clear into the existing mutex section, after the RCU pointer is cleared.

Affected products

Linux: from 6.1.191 before 6.2; from 6.6.160 before 6.7 — fixed in 6.2, 6.7

How to fix

Upgrade to a fixed version: Linux 6.2, 6.7. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-90373 or the next vulnerability affects your stack