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CVE-2021-27561

96
FAUCET Score

CVE-2021-27561 is a critical unauthenticated command injection vulnerability in Yealink Device Management (DM) version 3.6.0.20, specifically affecting the /sm/api/v1/firewall/zone/services URI. With a CVSS score of 9.8, this flaw allows remote attackers to execute arbitrary commands as root with no user interaction required, leading to complete compromise of confidentiality, integrity, and availability. This vulnerability is actively exploited in the wild, as evidenced by its inclusion in CISA's KEV catalog and mentions in media coverage regarding botnet activity. While no Metasploit or ExploitDB modules exist, Nuclei templates are available, and there is significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 3.6.0.20CPE matchmatch criteria
cpe:2.3:a:yealink:device_management:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
82.52%
Probability of exploitation in next 30 days
EPSS Percentile
99.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Added to KEV · Nov 3, 2021
Nuclei: CVE-2021-27561 · Aug 2, 2021
This CVE's current EPSS score of 0.8252 is in the 98th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
ssd-disclosure.com
Third Party Advisory