CVE-2021-27561 Yealink CVE debrief

Who should care

Organizations running Yealink Device Management, plus vulnerability management, IT operations, and security teams responsible for patching internet-facing or internally reachable management systems.

Technical summary

The supplied sources identify the issue only as a Server-Side Request Forgery (SSRF) vulnerability in Yealink Device Management. No additional technical details, affected versions, or exploit conditions are provided in the supplied corpus, but the CISA KEV listing indicates confirmed exploitation risk and directs defenders to apply vendor updates.

Defensive priority

High / urgent. CISA added this CVE to the Known Exploited Vulnerabilities catalog and set a remediation due date of 2021-11-17, so affected environments should be prioritized for update and validation.

Recommended defensive actions

• Apply Yealink updates per vendor instructions.
• Inventory Yealink Device Management deployments to confirm exposure and scope.
• Prioritize remediation before or immediately after other routine maintenance items because the issue is KEV-listed.
• Validate that affected systems are no longer running vulnerable versions after patching.
• Track for any compensating controls or internal exceptions until remediation is complete.

Evidence notes

Evidence is limited to official records and CISA KEV metadata. The corpus confirms the product, vulnerability class, and KEV status, but does not provide CVSS, affected versions, attack preconditions, or exploitation details. No unsupported technical claims are included.

Official resources