CVE-2021-27245: TP-Link Archer a7 Firmware

High severity, CVSS 8.1. EPSS: 3.2% chance of exploitation in the next 30 days.

This vulnerability allows a firewall bypass on affected installations of TP-Link Archer A7 prior to Archer C7(US)_V5_210125 and Archer A7(US)_V5_200220 AC1750 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of IPv6 connections. The issue results from the lack of proper filtering of IPv6 SSH connections. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of root. Was ZDI-CAN-12309.

Affected products

• TP-Link Archer a7 Firmware: before c7\(us\)_v5_210125 (fixed in c7\(us\)_v5_210125); before a7\(us\)_v5_200220 (fixed in a7\(us\)_v5_200220)

Published 2021-03-29. Last modified 2026-06-17.