CVE-2026-93271 wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate
An attacker within WiFi range can cause valid frames to be dropped by triggering a kernel warning via out-of-range MCS values in ath11k driver.
- 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-2026-93271?
CVE-2026-93271 is a denial of service vulnerability in Linux, published on 24 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:
wifi: ath11k: cap out-of-range rx MCS instead of leaving bogus rate
ath11k can receive HT/VHT/HE frames whose reported MCS is above the maximum that can be expressed in the corresponding mac80211 rate space (e.g. an HE frame reported with MCS 12, while HE tops out at MCS 11).
The frame itself is valid and decodes correctly, but for such a frame ath11k_dp_rx_h_rate() leaves rx_status->rate_idx set to the out-of-range value and never assigns rx_status->encoding, so it stays RX_ENC_LEGACY from the ath11k_dp_rx_h_ppdu() initialization. Once that frame reaches mac80211 it trips the rate sanity check and the frame is dropped with a splat:
ath11k_pci 0000:03:00.0: Received with invalid mcs in HE mode 12 WARNING: CPU: 0 PID: 0 at net/mac80211/rx.c:5433 ieee80211_rx_list+0xb0a/0xe90 [mac80211]
Dropping the frame would discard otherwise valid data, so instead cap the reported MCS to the maximum the rate space can express and deliver the frame. Set rx_status->encoding before the range check and assign rate_idx from the capped value, so a frame with an out-of-range MCS no longer leaves partial or bogus rate metadata behind. Also downgrade the logging level since they are not treated as invalid frames now. The only loss is that such a frame is reported as the capped MCS in the rx rate statistics.
Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41
Which versions are affected by CVE-2026-93271?
How do I fix CVE-2026-93271?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-93271 being exploited?
There is no known exploitation of CVE-2026-93271 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93271, DEBIAN-CVE-2026-93271, GHSA-322g-prc2-r52c, UBUNTU-CVE-2026-93271.