CVE-2021-27209Public exploit

Credential theft via cleartext Base64 session cookie

Published Feb 13, 2021 · Updated Aug 3, 2024

Cleartext credential transmission in TP-Link Archer C5v 1.7_181221 allows attackers to capture administrator credentials over HTTP. The management interface stores the authenticated user's username and password in a Base64-encoded cookie and transmits it without TLS. An attacker with local-network visibility can decode a captured cookie and use the recovered credentials to access the management interface.

CVSS severity7.1
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cleartext credential transmission in TP-Link Archer C5v 1.7_181221 allows attackers to capture administrator credentials over HTTP. The management interface stores the authenticated user's username and password in a Base64-encoded cookie and transmits it without TLS. An attacker with local-network visibility can decode a captured cookie and use the recovered credentials to access the management interface.

The record

CVE
CVE-2021-27209
Published
Feb 13, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-319, T1040
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-319Cleartext Transmission of Sensitive Information
T1040Network Sniffing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo