CVE-2026-74649: staging: rtl8723bs: fix missing shared-key auth challenge length check
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 chgtxt buffer.
In OnAuthClient() the length from rtwgetie() - up to 255 - is used to perform memcpy() into the 128-byte pmlmeinfo->chgtxt, so a malicious AP sending a malformed WLANEIDCHALLENGE element can overflow/underfill chgtxt 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 WLANAUTHCHALLENGELEN define; require the element to be exactly that length before use.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Systems using the Linux kernel's staging rtl8723bs driver are exposed when they perform WEP shared-key authentication with an access point. The vulnerable path is reached before association.
What does an attacker need to exploit it?
An attacker needs to operate or impersonate a malicious WLAN access point within wireless range and send a malformed WLAN_EID_CHALLENGE element during shared-key authentication. No prior association is required.
What are the potential effects of malformed challenge text?
A challenge element longer than 128 bytes can cause an out-of-bounds write in the driver. A shorter element can cause the driver to echo stale data from the challenge buffer.