CVE-2022-43636 Auth bypass in TL-WR940N

High 7.5 Published 29 Mar 2023 Updated 12 Feb 2025

Network-adjacent attackers can bypass authentication on TP-Link TL-WR940N routers due to insufficient randomness in session sequence numbers.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2022-43636?

CVE-2022-43636 is a high-severity authentication bypass vulnerability in TP-Link TL-WR940N, published on 29 Mar 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of TP-Link TL-WR940N 6_211111 3.20.1(US) routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the httpd service, which listens on TCP port 80 by default. The issue results from the lack of sufficient randomness in the sequnce numbers used for session managment. An attacker can leverage this vulnerability to bypass authentication on the system. Was ZDI-CAN-18334.

Weakness: CWE-330

Which versions are affected by CVE-2022-43636?

It affects 1 product.

Products include Tp-Link Tl-Wr940n Firmware.

How do I fix CVE-2022-43636?

No fix has been published for CVE-2022-43636 yet. Limit exposure of the affected software until one is available.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2022-43636 being exploited?

There is no known exploitation of CVE-2022-43636 in the wild and no public exploit code.

Sources

Also known as GHSA-3fvg-68xh-vfxq.