ZDI-CAN-18334: TP-Link TL-WR940N httpd Use of Insufficiently Random Values Authentication Bypass Vulnerability

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of TP-Link TL-WR940N 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.

Affected Software

1 affected component
TP-Link TL-WR940N

Event History

Mar 24, 2025
Advisory Published
via ZDI·03:10 PM
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Frequently Asked Questions

1

What is the severity of ZDI-CAN-18334?

The severity of ZDI-CAN-18334 is critical due to its ability to allow network-adjacent attackers to bypass authentication.

2

How do I fix ZDI-CAN-18334?

To fix ZDI-CAN-18334, update the firmware of the TP-Link TL-WR940N router to the latest version provided by TP-Link.

3

What impact does ZDI-CAN-18334 have on my device?

ZDI-CAN-18334 allows unauthorized access to the TP-Link TL-WR940N router, potentially compromising network security.

4

Who is affected by ZDI-CAN-18334?

Users of the TP-Link TL-WR940N routers are affected by ZDI-CAN-18334 due to the authentication bypass vulnerability.

5

Is authentication required to exploit ZDI-CAN-18334?

No, authentication is not required to exploit ZDI-CAN-18334, making it particularly dangerous.

Contact

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