CVE-2026-31394
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel mac80211 subsystem, a crash occurs during channel switch (CSA) for stations on AP_VLAN interfaces (e.g., 4addr WDS clients). ieee80211_chan_bw_change() uses sta->sdata pointing to VLAN without channel reservation, causing a NULL pointer dereference.
Risk Assessment
An attacker could trigger a kernel panic on systems with AP VLANs, leading to denial of service.
Recommendation
Apply the kernel patch that resolves VLAN sdata to parent AP before accessing link data. Update the kernel to a fixed version.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: mac80211: fix crash in ieee80211_chan_bw_change for AP_VLAN stations ieee80211_chan_bw_change() iterates all stations and accesses link->reserved.oper via sta->sdata->link[link_id]. For stations on AP_VLAN interfaces (e.g. 4addr WDS clients), sta->sdata points to the VLAN sdata, whose link never participates in chanctx reservations. This leaves link->reserved.oper zero-initialized with chan == NULL, causing a NULL pointer dereference in __ieee80211_sta_cap_rx_bw() when accessing chandef->chan->band during CSA. Resolve the VLAN sdata to its parent AP sdata using get_bss_sdata() before accessing link data. [also change sta->sdata in ARRAY_SIZE even if it doesn't matter]