Actively exploited in the wild
Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability
Yealink - Device Management · Listed in the CISA KEV since 2021-11-03. This indicates confirmed attacks in production environments.
Required action: Apply updates per vendor instructions.
CVE-2021-27561
CriticalCVSS 9.8KEVSummary
Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication. The vulnerability enables remote execution of system commands with the highest privileges.
Risk Assessment
An attacker can execute arbitrary commands as root, leading to full device compromise and potential lateral movement. The lack of authentication makes the vulnerability easy to exploit.
Recommendation
Upgrade Yealink Device Management to the latest version containing the fix. If upgrade is not possible, restrict access to the API interface and monitor for unusual commands.
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Original NVD description (English source)
Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication.