CVE-2026-98340

About vulnerability

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.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Debian 10 ELS , Debian 11 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 5.4.0 (+17 more)

Live-patch status from KernelCare for each operating system.