CVE-2025-38509: wifi: mac80211: reject VHT opmode for unsupported channel widths

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-16 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: reject VHT opmode for unsupported channel widths VHT operating mode notifications are not defined for channel widths below 20 MHz. In particular, 5 MHz and 10 MHz are not valid under the VHT specification and must be rejected. Without this check, malformed notifications using these widths may reach ieee80211_chan_width_to_rx_bw(), leading to a WARN_ON due to invalid input. This issue was reported by syzbot. Reject these unsupported widths early in sta_link_apply_parameters() when opmode_notif is used. The accepted set includes 20, 40, 80, 160, and 80+80 MHz, which are valid for VHT. While 320 MHz is not defined for VHT, it is allowed to avoid rejecting HE or EHT clients that may still send a VHT opmode notification.

Affected products

Linux kernel: from 6.13 before 6.15.7; 6.16-rc1, 6.16-rc2, 6.16-rc3, 6.16-rc4, 6.16-rc5 — fixed in 6.15.7

How to fix

Upgrade to a fixed version: Linux kernel 6.15.7. Check the vendor advisory for mitigations.

References

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