# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-93271, DEBIAN-CVE-2026-93271, GHSA-322g-prc2-r52c, UBUNTU-CVE-2026-93271

## 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.

## Is CVE-2026-93271 being exploited?

There is no known exploitation of CVE-2026-93271 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93271 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-93271 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93271/ (Markdown: https://insights.sbomify.com/CVE-2026-93271/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93271
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93271
- OSV: https://osv.dev/vulnerability/CVE-2026-93271

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93271/
Summaries are generated and may contain mistakes; the official description above is the record.