# CVE-2026-98340: wifi: cfg80211: only group hidden BSSes with beacon entries

> A logic error in Linux kernel Wi-Fi handling allows attackers to trigger kernel warnings and potential instability via crafted probe responses.

- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106179, BELL-CVE-2026-98340, DEBIAN-CVE-2026-98340, GHSA-84vw-9582-fhpx, UBUNTU-CVE-2026-98340

## What is CVE-2026-98340?

CVE-2026-98340 is a denial of service vulnerability in Linux, published on 6 Oct 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: cfg80211: only group hidden BSSes with beacon entries

When a probe response for an unknown BSS comes in, __cfg80211_bss_update()
looks for an existing entry with the same BSSID and a hidden (zero-length
or NUL-filled) SSID, and if it finds one it groups them, using the beacon
IEs from the existing entry.

But that could find another entry without a beacon, if it was also from a
probe response (with SSID), so there's a group without beacon elements.

If a beacon with a hidden SSID for that BSSID arrives later,
cfg80211_combine_bsses() goes looking for the probe response entries that
belong to it - i.e. entries with the same BSSID and channel that have no
beacon IEs - and finds those two. They are already grouped with each
other, so it hits its

  WARN_ON_ONCE(bss->pub.hidden_beacon_bss)
  WARN_ON_ONCE(!list_empty(&bss->hidden_list))

which are there because an entry without beacon elements is not supposed
to be part of a group yet.

Only combine entries when a beacon was already received, ones that are
kept separate will be combined when a beacon arrives.

## Which versions are affected by CVE-2026-98340?


## How do I fix CVE-2026-98340?

Apply the vendor's patch.

## Is CVE-2026-98340 being exploited?

There is no known exploitation of CVE-2026-98340 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98340 and fix it if it is affected.

What it is: CVE-2026-98340 is a denial of service vulnerability in Linux, published on 6 Oct 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-2026-98340 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-2026-98340/ (Markdown: https://insights.sbomify.com/CVE-2026-98340/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98340
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98340
- OSV: https://osv.dev/vulnerability/CVE-2026-98340

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98340/
Summaries are generated and may contain mistakes; the official description above is the record.