CVE-2021-27245

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-03-29 · updated 2026-06-17
Weakness: CWE-693

Description

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: before c7\(us\)_v5_210125; before a7\(us\)_v5_200220 — fixed in a7\(us\)_v5_200220, c7\(us\)_v5_210125

How to fix

Upgrade to a fixed version: TP-Link Archer A7 a7\(us\)_v5_200220, c7\(us\)_v5_210125. Check the vendor advisory for mitigations.

References

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