What is CVE-2021-27209?

CVE-2021-27209 is a high-severity vulnerability in TP-Link Archer C5v, classified under Cleartext Transmission of Sensitive Information. CVSS score: 7.1/10. Published 2021-02-13.

How severe is CVE-2021-27209?

High severity. CVSS v3 base score is 7.1 out of 10.

Vulnerability in TP-Link Archer C5v

CVE-2021-27209

In the management interface on TP-Link Archer C5v 1.7_181221 devices, credentials are sent in a base64 format over cleartext HTTP.

Published 2021-02-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.4th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

TP-Link Archer C5v — versions 1.0
TP-Link Archer C5v Firmware — versions 1.7_181221

Weakness classification (CWE)

CWE-319 — Cleartext Transmission of Sensitive Information

References

gokay.org/tp-link-archer-c5v-base64-cookie/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-27209?: CVE-2021-27209 is a high-severity vulnerability in TP-Link Archer C5v, classified under Cleartext Transmission of Sensitive Information. CVSS score: 7.1/10. Published 2021-02-13.
How severe is CVE-2021-27209?: High severity. CVSS v3 base score is 7.1 out of 10.