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PatchSiren cyber security CVE debrief

CVE-2021-27561 Yealink CVE debrief

CVE-2021-27561 is a Yealink Device Management server-side request forgery (SSRF) vulnerability that CISA added to the Known Exploited Vulnerabilities catalog on 2021-11-03. Because it is KEV-listed, defenders should treat remediation as urgent and follow vendor update guidance.

Vendor
Yealink
Product
Device Management
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

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.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-27561 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-27561

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-27561 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-27561

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.