No exploitation reportedFix available

CVE-2021-27245

Q: Is CVE-2021-27245 actively exploited?

Active exploitation of CVE-2021-27245 has not been confirmed. Its EPSS score was 3.3% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-27245?

CVE-2021-27245 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-03-29
Fixed inc7\(us\)_v5_210125 · a7\(us\)_v5_200220
WeaknessCWE-693

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2021-03-2921:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-27245?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27245?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Tp-link archer a7 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	< c7\(us\)_v5_210125	c7\(us\)_v5_210125	NVD
—	< a7\(us\)_v5_200220	a7\(us\)_v5_200220	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Tp-link archer a7 firmware to c7\(us\)_v5_210125 · a7\(us\)_v5_200220

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.1read 2026-10-23
CNACVSS 3.08.1read 2026-10-23
NVDCVSS 2.09.3read 2026-10-23
CNAweakness (CWE)CWE-693read 2026-10-23
FIRST EPSSEPSS score3.3 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-03-29
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-27245?

Is CVE-2021-27245 actively exploited?

Active exploitation of CVE-2021-27245 has not been confirmed. Its EPSS score was 3.3% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27245?

CVE-2021-27245 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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