TP-Link TL-WR841N: authentication bypass flaw under attack

What is affected

TP-Link TL-WR841N is the kind of equipment many homes and small offices run for years without touching: a router, camera or storage box. Attackers scan the internet for exposed units, and a hijacked one can spy on traffic or be enrolled in a botnet without any visible sign.

TP-Link TL-WR841N contains an authentication bypass by spoofing vulnerability within the httpd service, which listens on TCP port 80 by default, leading to the disclose of stored credentials. The impacted products could be end-of-life (EoL) and/or end-of-service (EoS). Users should discontinue product utilization.

What an attacker can do

This is a authentication bypass flaw. It lets an attacker get in without a valid username and password and act as a legitimate user, often as an administrator.

How it is reached

From the same local network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. Check whether you own this device: look at the label on your router, camera or NAS, or open its admin page and note the model and firmware version.
2. Install the latest firmware from the manufacturer's support page or the device's own update menu.
3. If the manufacturer no longer releases updates for the model, replace it. An end-of-life device with an exploited flaw cannot be made safe.
4. Turn off remote administration from the internet unless you truly need it, and change the default admin password.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• tp-link.comwww.tp-link.com/us/support/faq/4308/

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on September 3, 2025, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by September 24, 2025, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 16% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 97% of all scored vulnerabilities.

Its CVSS severity score is 6.5 out of 10 (medium), as recorded in the US National Vulnerability Database.

Technical description

TP-Link TL-WR841N dropbearpwd Improper Authentication Information Disclosure Vulnerability. This vulnerability allows network-adjacent attackers to disclose sensitive information on affected installations of TP-Link TL-WR841N 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 improper authentication. An attacker can leverage this vulnerability to disclose stored credentials, leading to further compromise. Was ZDI-CAN-19899.