IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2021-27561|Auth: none — unauthenticated|Reboot: required|Manual only

Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability (CVE-2021-27561)

Yealink Device Management contains a server-side request forgery (SSRF) vulnerability that allows for unauthenticated remote code execution.

Published Oct 15, 2021 · Updated May 17, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2021-11-17 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a OS Command Injection (CWE-78) vulnerability in Yealink Device Management. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

📧

Phishing link

→

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security
●Running device management: v ≤ 3.6.0.20
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2021-11-03 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2021-11-17.

How to patch

Manual remediation steps

1
Identify affected hosts: query inventory for general installs in scope.
2
Apply the vendor security update referenced in CVE-2021-27561's advisory. No specific KB/version is encoded yet — consult the linked MSRC/vendor URL.
3
Verify the fix per the vendor's published verification steps.
4
Document the remediation in your change ticket and re-scan with your vulnerability scanner to confirm closure.
PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ CVE-2021-27561↗ MSRC Advisory↗ NVD