CVE-2026-68402: wifi: cfg80211: bound element ID read when checking non-inheritance

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

wifi: cfg80211: bound element ID read when checking non-inheritance

cfg80211_is_element_inherited() reads the first data octet of the
candidate element (id = elem->data[0]) to look it up in an extension
non-inheritance list. It does so after testing elem->id, but without
verifying that the element actually has a data octet. A zero-length
extension element (WLAN_EID_EXTENSION with length 0) therefore makes it
read one octet past the end of the element.

_ieee802_11_parse_elems_full() runs this check for every element of a
frame once a non-inheritance context exists -- e.g. while parsing a
per-STA profile of a Multi-Link element in a (re)association response,
or a non-transmitted BSS profile -- so a crafted frame from an AP can
trigger a one-octet slab-out-of-bounds read during element parsing:

  BUG: KASAN: slab-out-of-bounds in cfg80211_is_element_inherited
  Read of size 1 ... in net/wireless/scan.c

Return early (treat the element as inherited) when an extension element
carries no data, mirroring the existing handling of empty ID lists.

The bug was found by fuzzing ieee802_11_parse_elems_full() under KASAN.

The Linux kernel CVE team has assigned CVE-2026-68402 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.2 with commit f7dacfb11475ba777e1e84ccec2e14b0ba5a17a3 and fixed in 6.6.148 with commit 20c308d9a57722801961f816395bf825f7bde6bc
	Issue introduced in 5.2 with commit f7dacfb11475ba777e1e84ccec2e14b0ba5a17a3 and fixed in 6.12.101 with commit 84bd907361c56fbd5523eceb2682cb39da059bd5
	Issue introduced in 5.2 with commit f7dacfb11475ba777e1e84ccec2e14b0ba5a17a3 and fixed in 6.18.42 with commit 11ac7a5e75f5132f1778e0c60981d30dc29fb869
	Issue introduced in 5.2 with commit f7dacfb11475ba777e1e84ccec2e14b0ba5a17a3 and fixed in 7.1.6 with commit ddf2773bcc8e49a43c561f22ec1e7924215d7947
	Issue introduced in 5.2 with commit f7dacfb11475ba777e1e84ccec2e14b0ba5a17a3 and fixed in 7.2-rc4 with commit cb8afea4655ff004fa7feee825d5c79783525383

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-68402
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/wireless/scan.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/20c308d9a57722801961f816395bf825f7bde6bc
	https://git.kernel.org/stable/c/84bd907361c56fbd5523eceb2682cb39da059bd5
	https://git.kernel.org/stable/c/11ac7a5e75f5132f1778e0c60981d30dc29fb869
	https://git.kernel.org/stable/c/ddf2773bcc8e49a43c561f22ec1e7924215d7947
	https://git.kernel.org/stable/c/cb8afea4655ff004fa7feee825d5c79783525383