CVE-2023-53570

An integer overflow flaw was found in the Linux kernel's nl80211 wireless configuration interface in the MBSSID element parsing logic. A local user with CAP_NET_ADMIN capability can trigger this issue by specifying 256 or more MBSSID elements through the nl80211 interface, causing the u8 counter num_elems to wrap to zero. This results in a heap buffer overflow when the code allocates space based on the wrapped value but then writes data for all supplied elements, leading to memory corruption and denial of service through kernel crash.

The nl80211_parse_mbssid_elems function counts MBSSID (Multiple BSSID) configuration elements using a u8 variable that can only represent values 0-255. When userspace provides 256 or more elements, the counter wraps to zero due to integer overflow. The function then allocates a structure with a trailing array sized according to num_elems, but subsequently iterates through all supplied elements in attrs, writing beyond the allocated buffer. This heap overflow can cause memory corruption affecting kernel stability. The vulnerability only affects wireless devices where the driver sets wiphy->mbssid_max_interfaces, and exploitation requires CAP_NET_ADMIN capability, limiting the attack surface to privileged network configuration operations. The fix enforces a maximum of 255 elements.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.