How severe is CVE-2021-27245?

CVE-2021-27245 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27245 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27245?

CVE-2021-27245 affects Tp-link Archer A7 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27245?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-27245 published?

CVE-2021-27245 was published on 2021-03-29 and last updated on 2026-06-17.

CVE-2021-27245

CVE-2021-27245 is a high-severity vulnerability in Tp-link Archer A7 Firmware with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-693.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 9.3
EPSS exploit prediction: 3% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-693
Affected product: Tp-link Archer A7 Firmware
Published: 2021-03-29
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-27245?: 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.
How severe is CVE-2021-27245?: CVE-2021-27245 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27245 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27245?: CVE-2021-27245 affects Tp-link Archer A7 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27245?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27245 published?: CVE-2021-27245 was published on 2021-03-29 and last updated on 2026-06-17.

References

https://www.zerodayinitiative.com/advisories/ZDI-21-214/

Affected products (1)

cpe:2.3:o:tp-link:archer_a7_firmware:*:*:*:*:*:*:*:*

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