CVE-2026-74649: staging: rtl8723bs: fix missing shared-key auth challenge length check

From: Greg Kroah-Hartman <[email protected]>

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

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

staging: rtl8723bs: fix missing shared-key auth challenge length check

The WEP shared-key authentication handler uses the challenge-text
element's attacker-controlled length without checking it against the
fixed 128-byte chg_txt buffer.

In OnAuthClient() the length from rtw_get_ie() - up to 255 - is used
to perform memcpy() into the 128-byte pmlmeinfo->chg_txt, so a
malicious AP sending a malformed WLAN_EID_CHALLENGE element can
overflow/underfill chg_txt by up to 127 bytes. It is reachable over the
air, before association, during shared-key authentication. In the case
of an overflow, the driver can write out of bounds. In the case of an
underfill, the driver can echo stale buffer memory.

The challenge text is defined to be exactly 128 octets, which is
already provided as the WLAN_AUTH_CHALLENGE_LEN define; require the
element to be exactly that length before use.

The Linux kernel CVE team has assigned CVE-2026-74649 to this issue.


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

	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 5.15.216 with commit 39ae1033071001af9bb4573ebdbb43bbbe88f749
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 6.1.183 with commit 4d018e7d7d908bdfcb5ecfa922b1d5cb9ddb3722
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 6.6.152 with commit 4ba402fd47009d20e51dbfc934abb562098ea35b
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 6.12.104 with commit 87c2f073d2aaea041d531b8e579c47570b54b3b7
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 6.18.45 with commit a28a4b0592e4a37ea471bc0d308513a93133ce7e
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 7.1.9 with commit 6235b5156b48ed5d1ce3410d8f0b2fd67d30d944
	Issue introduced in 4.12 with commit 554c0a3abf216c991c5ebddcdb2c08689ecd290b and fixed in 7.2 with commit 2c56ef658ac8c6bca36bc5574715e8f717207c6c

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-2026-74649
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:
	drivers/staging/rtl8723bs/core/rtw_mlme_ext.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/39ae1033071001af9bb4573ebdbb43bbbe88f749
	https://git.kernel.org/stable/c/4d018e7d7d908bdfcb5ecfa922b1d5cb9ddb3722
	https://git.kernel.org/stable/c/4ba402fd47009d20e51dbfc934abb562098ea35b
	https://git.kernel.org/stable/c/87c2f073d2aaea041d531b8e579c47570b54b3b7
	https://git.kernel.org/stable/c/a28a4b0592e4a37ea471bc0d308513a93133ce7e
	https://git.kernel.org/stable/c/6235b5156b48ed5d1ce3410d8f0b2fd67d30d944
	https://git.kernel.org/stable/c/2c56ef658ac8c6bca36bc5574715e8f717207c6c