CVE-2021-27561 (GCVE-0-2021-27561)
Vulnerability from cvelistv5 – Published: 2021-10-15 17:11 – Updated: 2025-10-21 23:25Summary
Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication.
Severity
9.8 (Critical)
SSVC
Exploitation: active
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-02-04 19:33 UTC
CWE
- n/a
- CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://ssd-disclosure.com/?p=4688 | x_refsource_MISC |
| https://www.cisa.gov/known-exploited-vulnerabilit… | government-resource |
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: df5a51f1-8bbc-4b3e-8766-899f87bd6736
Exploited: Yes
Timestamps
First Seen: 2021-11-03
Asserted: 2021-11-03
Scope
Notes: Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability | Affected: Yealink / Device Management | Description: Yealink Device Management contains a server-side request forgery (SSRF) vulnerability that allows for unauthenticated remote code execution. | Required action: Apply updates per vendor instructions. | Due date: 2021-11-17 | Known ransomware campaign use (KEV): Unknown | Notes (KEV): https://nvd.nist.gov/vuln/detail/CVE-2021-27561
Evidence
Type: Vendor Report
Signal: Successful Exploitation
Confidence: 80%
Source: cisa-kev
Details
| Cwes | CWE-78 |
|---|---|
| Feed | CISA Known Exploited Vulnerabilities Catalog |
| Product | Device Management |
| Due Date | 2021-11-17 |
| Date Added | 2021-11-03 |
| Vendorproject | Yealink |
| Vulnerabilityname | Yealink Device Management Server-Side Request Forgery (SSRF) Vulnerability |
| Knownransomwarecampaignuse | Unknown |
References
Created: 2026-10-02 08:10 CEST
| Updated: 2026-10-02 08:10 CEST
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 137265dd-d850-4d39-a042-aec078130363
Exploited: Yes
Timestamps
First Seen: 2021-11-03
Asserted: 2021-11-03
Scope
Notes: Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication. | Affected: Yealink / Device Management | CVSS: 9.8 (CRITICAL) | EPSS: 0.82865 | Used in malware: unknown | Not yet in CISA KEV: False
Evidence
Type: Public Report
Signal: Successful Exploitation
Confidence: 70%
Source: previdian
Details
| Feed | Previdian (previdian.com) |
|---|---|
| Title | Yealink Device Management (DM) 3.6.0.20 allows command injection as root via the /sm/api/v1/firewall/zone/services URI, without authentication. |
| Cve Id | CVE-2021-27561 |
| Vendor | Yealink |
| Ghsa Id | None |
| Product | Device Management |
| Added Date | 2021-11-03T00:00:00.000Z |
| Cvss Score | 9.8 |
| Epss Score | 0.82865 |
| Previous Ids | |
| Cvss Severity | CRITICAL |
| Virtual Patch | False |
| Cvss Estimated | False |
| Epss Percentile | 0.99663 |
| Used In Malware | unknown |
| Vulnerability Id | CVE-2021-27561 |
| Ahead Of Cisa Kev | None |
| Not Yet In Cisa Kev | False |
References
Created: 2026-10-02 09:10 CEST
| Updated: 2026-10-02 09:10 CEST
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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