CVE-2026-93805

Status: UPDATED  |  Advisory ID: CVE-2026-93805

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

wifi: cfg80211: validate rx/tx MLME callback frame lengths before access

cfg80211_rx_mlme_mgmt() and cfg80211_tx_mlme_mgmt() call tracepoints

before rejecting frames shorter than the frame-control field. After

that, they only require len >= 2 before dispatching into subtype

handlers that assume their fixed fields are present.

The frames that trip this are not shorter than 2 bytes; they are short

relative to their subtype. mwifiex is a concrete in-tree example on the

length side: mwifiex_process_mgmt_packet() only requires a 4-address

ieee80211_hdr plus the 2-byte firmware length prefix before handing the

frame to cfg80211_rx_mlme_mgmt(). After stripping the length prefix and

removing addr4, pkt_len can be exactly 24: a bare 3-address management

header with no reason-code body. The existing WARN_ON(len < 2) does not

fire on such a frame, and cfg80211_process_deauth() then reads

u.deauth.reason_code as a two-byte access starting at offset 24,

immediately past the 24-byte buffer.

Add a frame-control length gate, then validate each subtype's minimum

frame size in an if/else-if chain that mirrors the dispatch logic. Trace

only after the frame is known to be well-formed.

Side effects of this change:

- The WARN_ON(len < 2) is dropped. It only guarded the frame_control

read, never the subtype fixed fields, and it does not fire on the

frames that actually trigger the out-of-bounds read (which are >= 2).

The len >= 2 check is kept as the guard before dereferencing

frame_control, but without the warning: these are exported callbacks

and a malformed frame from a driver should be dropped silently rather

than backtraced.

- cfg80211_tx_mlme_mgmt() previously routed every non-deauth subtype

through disassociation handling; it now silently ignores unrecognised

subtypes. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References