High · published August 10, 2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: at76c50x-usb: avoid length underflow in at76_guess_freq()
at76_guess_freq() checks only that the received frame is at least a bare
802.11 header (24 bytes) before subtracting the fixed management-body
offset:
len -= el_off;
For both beacon and probe response frames, el_off is 36. If the frame is
shorter than el_off, subtracting it causes the calculated IE length to
wrap. The length is eventually passed to cfg80211_find_elem_match() as a
very large unsigned value, so the element walk runs beyond the RX skb.
This path is reached from at76_rx_tasklet() while scanning. If the device
delivers a truncated beacon or probe response, the oversized IE length
causes an out-of-bounds read during scanning.
Skip the IE lookup if the frame does not reach the variable elements,
before subtracting el_off.