CVE-2026-98340

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.

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EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/068843ed0902c552a13860c5ec6b2ca65b57a065 https://git.kernel.org/stable/c/332ea1502c46f53375cb109fa82bfaff818f3a41 https://git.kernel.org/stable/c/3658093df69849daf4f813a8f087f358e13be203 https://git.kernel.org/stable/c/4cd6a518ce7527284bbc9baab5fa2453a7d477c2 https://git.kernel.org/stable/c/73365b81630b57e1a1f9d50dc87281797855c2ac https://git.kernel.org/stable/c/7405dd19bda4537a2843637d8d7bed1efd4776cf https://git.kernel.org/stable/c/74ed0d992f392c75e1969415527e06df3f7a4034 https://git.kernel.org/stable/c/86235be788094131912e9bd8412b358d91d99f49

Frequently Asked Questions

What is CVE-2026-98340? +

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.

How do I check if I'm vulnerable to CVE-2026-98340? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.