CVE-2021-27245

TP-Link Archer A7 Protection Mechanism Failure Firewall Bypass Vulnerability

Severity Score

8.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Esta vulnerabilidad permite una omisión del firewall en las instalaciones afectadas de TP-Link Archer A7 antes de los enrutadores Archer C7(EE. UU.)_V5_210125 y Archer A7(EE. UU.)_V5_200220 AC1750. No es requerida una autenticación para explotar esta vulnerabilidad. El fallo específico se presenta dentro del manejo de las conexiones IPv6. El problema resulta de una falta de filtrado apropiado de las conexiones SSH IPv6. Un atacante puede aprovechar esto junto con otras vulnerabilidades para ejecutar código en el contexto de root. Era ZDI-CAN-12309

This vulnerability allows a firewall bypass on affected installations of TP-Link Archer A7 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.

*Credits: Team FLASHBACK: Pedro Ribeiro (@pedrib1337 | pedrib@gmail.com) + Radek Domanski (@RabbitPro)

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Medium

Authentication

None

Confidentiality

Complete

Integrity

Complete

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-02-16 CVE Reserved
2021-02-24 CVE Published
2023-12-27 EPSS Updated
2024-08-03 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-693: Protection Mechanism Failure

CAPEC

References (1)

URL	Tag	Source
https://www.zerodayinitiative.com/advisories/ZDI-21-214	Third Party Advisory

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Tp-link Search vendor "Tp-link"	Archer A7 Firmware Search vendor "Tp-link" for product "Archer A7 Firmware"	< c7\(us\)_v5_210125 Search vendor "Tp-link" for product "Archer A7 Firmware" and version " < c7\(us\)_v5_210125"	-	Affected	in	Tp-link Search vendor "Tp-link"	Archer A7 Search vendor "Tp-link" for product "Archer A7"	-	-	Safe
Tp-link Search vendor "Tp-link"	Archer A7 Firmware Search vendor "Tp-link" for product "Archer A7 Firmware"	< a7\(us\)_v5_200220 Search vendor "Tp-link" for product "Archer A7 Firmware" and version " < a7\(us\)_v5_200220"	-	Affected	in	Tp-link Search vendor "Tp-link"	Archer A7 Search vendor "Tp-link" for product "Archer A7"	-	-	Safe