JFrog Security Research

XRAY-194066 - Realtek RTL8195A DoS

CVE-2020-25857 | CVSS 7.5

JFrog Severity:high

Published 3 Feb. 2021 | Last updated 3 Feb. 2021

A stack buffer overflow in the Realtek RTL8195A Wi-Fi Module allows unauthenticated attackers in wireless range to cause denial of service by impersonating a Wi-Fi access point

Realtek Ameba SDK

Ameba SDK (, 2.0.8), fixed in 2.0.8

Realtek Wi-Fi chips enable connectivity for embedded devices and are widely used in IoT development boards and production devices. This vulnerability affects the RTL8195A module. Attackers can exploit the module by impersonating an Access Point (AP) and injecting a packet into the WPA2 handshake to cause a stack buffer overflow, crashing the device and causing denial of service. No public exploit is currently known for this vulnerability, but the JFrog blog provides sufficient technical details for an attacker to replicate the exploit. The firmware employs no mitigations against memory corruption attacks, such as stack canaries, the NX bit, or ASLR protections, making this easier to exploit. Since this is a Wi-Fi attack, the attacker must be close enough for the target device to connect to the attacker's AP. The function ClientEAPOLKeyRecvd in the Wi-Fi module's firmware does not validate the length parameter for an rtl_memcpy operation. The operation takes a length value provided on the network, and its the destination is a fixed-size stack buffer. This results in stack buffer overflow, but the attacker cannot control the overflowing source data, and so this can only be exploited to crash the device.

No PoC is supplied for this issue

No vulnerability mitigations are supplied for this issue

(JFrog) WiFi Vulnerabilities Discovered by Automated Zero-Day Analysis