CVE-2021-27245 - CVE House
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Status published High CVE-2021-27245

This vulnerability allows a firewall bypass on affected installations of...

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

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

References

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Affected Vendor

Affected Software

Archer A7
Vulnerable Versions:
prior to Archer C7(US)_V5_210125 and Archer A7(US)_V5_200220

Timeline

Official Publish: March 29th, 2021
Last Modified: August 3rd, 2024
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses (CWE)

CWE-693

MITRE ATT&CK TTPs

T1562 Impair Defenses
Defense Evasion
T1190 Exploit Public-Facing Application
Initial Access
T1068 Exploitation for Privilege Escalation
Privilege Escalation
T1550 Use Alternate Authentication Material
Defense Evasion
T1485 Data Destruction
Impact