{"id":"CVE-2021-27561","published":"2021-10-15T18:15:07Z","modified":"2026-06-17T03:45:08Z","title":"Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability","vendor":"Yealink","product":"Device Management","tier":"core","eol":null,"description":{"text":"Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication.","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is a command injection weakness in the Yealink Device Management (DM) server component, specifically in the handling of the /sm/api/v1/firewall/zone/services URI. An attacker can exploit it without authentication, over the network, and without any user interaction to inject commands that run as root.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-30T13:36:01Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.82865,"percentile":0.9967,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":false,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-27561","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-03-15","exploitedFirstSeen":"2021-03-15","ransomware":false,"evidence":[{"url":"https://unit42.paloaltonetworks.com/mirai-variant-iot-vulnerabilities/","date":"2021-03-15"},{"url":"https://www.fortinet.com/blog/threat-research/the-ghosts-of-mirai","date":"2021-06-24"},{"url":"https://www.radware.com/getmedia/18d24c2d-c092-4a61-9ad6-ebb92b7a49b8/Alert_Realtek_SDK.aspx","date":"2021-08-24"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2021-11-03"},{"url":"https://www.fortinet.com/blog/threat-research/Iz1h9-campaign-enhances-arsenal-with-scores-of-exploits","date":"2023-10-09"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2023-12-05&host_type=src&vulnerability=cve-2021-27561","date":"2023-12-05"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-01&host_type=src&vulnerability=cve-2021-27561","date":"2024-01-01"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-22&host_type=src&vulnerability=cve-2021-27561","date":"2024-01-22"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-23&host_type=src&vulnerability=cve-2021-27561","date":"2024-01-23"},{"url":"https://dashboard.shadowserver.org/statistics/honeypot/vulnerability/map/?day=2024-01-24&host_type=src&vulnerability=cve-2021-27561","date":"2024-01-24"}],"evidenceTotal":542,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev 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2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-78","name":"Improper Neutralization of Special Elements used in an OS Command"}],"references":[{"url":"https://ssd-disclosure.com/?p=4688","tags":["Third Party Advisory"]},{"url":"https://ssd-disclosure.com/?p=4688","tags":["Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-27561","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: 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expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-14312","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-14312","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":{"nuclei":[{"id":"CVE-2021-27561","name":"YeaLink DM 3.6.0.20 - Remote Command Injection","severity":"critical","path":"http/cves/2021/CVE-2021-27561.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-27561.yaml"}],"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2021-03-15","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://unit42.paloaltonetworks.com/mirai-variant-iot-vulnerabilities/","provenance":"source"},{"date":"2021-10-15","kind":"published","label":"Published 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