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

Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-09892592efe8, updated 2026-11-02T23:39:54.475Z.

CISA Known Exploited Vulnerabilities

Name
Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability
Vendor
Yealink
Product
Device Management
Added to the catalog
2021-11-03
Due date for US federal agencies
2021-11-17
Weaknesses
CWE-78
Catalog version
2026.10.30

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

Required action (CISA)

Apply updates per vendor instructions.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status
Analyzed
Published
2021-10-15T18:15:07.490
Last modified
2026-06-17T03:45:08.230
Weaknesses
CWE-78

Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication.

MetricScoreSeverityVectorScored by
CVSS 3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H[email protected] (Primary)
CVSS 3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
CVSS 2.010HIGHAV:N/AC:L/Au:N/C:C/I:C/A:C[email protected] (Primary)

References

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:59.479Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-27561

CVE record

Assigner
mitre
State
PUBLISHED
Published
2021-10-15T17:11:45.000Z
Updated
2025-10-21T23:25:28.403Z
Problem types
n/a

Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication.

References

Read on 2026-11-03T01:07:05.763Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2021/27xxx/CVE-2021-27561.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

D3FEND ontology version 1.6.0.

Read on 2026-11-02T23:54:16.526Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-78.json

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"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

Sources and licences

  • CISA

    Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.

    CC0 1.0 Universal

  • National Vulnerability Database (NIST)

    This product uses the NVD API but is not endorsed or certified by the NVD.

    NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)

  • CVE Program, The MITRE Corporation

    Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation. CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

    CVE Program Terms of Use ("CVE Usage" licence)

  • MITRE D3FEND

    MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
    "The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

    MITRE D3FEND Terms of Use (site + knowledge graph); source repo MIT

Cite this page

Dragons Eye Ransomware Tracker, "CVE-2021-27561: Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability",
entity page, dataset version ref-09892592efe8, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2021-27561 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-06-17T03:45:08.230.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2025-10-21T23:25:28.403Z.
Underlying source: MITRE D3FEND, ontology version 1.6.0.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.

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