The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code execution via a crafted payload in an IP address input field.

In TP-Link Wireless N Router WR840N an ARP poisoning attack can cause buffer overflow

oal_ipt_addBridgeIsolationRules on TP-Link TL-WR840N 6_EU_0.9.1_4.16 devices allows OS command injection because a raw string entered from the web interface (an IP address field) is used directly for a call to the system library function (for iptables). NOTE: oal_ipt_addBridgeIsolationRules is not the only function that calls util_execSystem.

The traceroute function on the TP-Link TL-WR840N v4 router with firmware through 0.9.1 3.16 is vulnerable to remote code execution via a crafted payload in an IP address input field.

TP-Link TL-WR840N v5 00000005 devices allow XSS via the network name. The attacker must log into the router by breaking the password and going to the admin login page by THC-HYDRA to get the network name. With an XSS payload, the network name changed automatically and the internet connection was disconnected. All the users become disconnected from the internet.

TP-Link TL-WR840N devices allow remote attackers to cause a denial of service (networking outage) via fragmented packets, as demonstrated by an "nmap -f" command.

TP-Link WR840N devices have a buffer overflow via a long Authorization HTTP header.

An issue was discovered on TP-Link TL-WR840N v5 00000005 0.9.1 3.16 v0001.0 Build 170608 Rel.58696n and TL-WR841N v13 00000013 0.9.1 4.16 v0001.0 Build 170622 Rel.64334n devices. This issue is caused by improper session handling on the /cgi/ folder or a /cgi file. If an attacker sends a header of "Referer: http://192.168.0.1/mainFrame.htm" then no authentication is required for any action.

Cross-site request forgery (CSRF) vulnerability in the administration console in TP-Link TL-WR840N (V1) router with firmware before 3.13.27 build 141120 allows remote attackers to hijack the authentication of administrators for requests that change router settings via a configuration file import.