RCE in Yealink Device Management

CVE-2021-27561

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

Vulnerability class: Command Injection (OS Command Injection)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.829 (99.7th percentile), scored .

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-27561: held from 0.829 to 0.829.

EPSS over last 30 days · oldest: 0.829 · newest: 0.829 · change: 0.000

Affected products

Weakness classification (CWE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: .

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-27561?
CVE-2021-27561 is a critical-severity vulnerability in Yealink Device Management, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-10-15.
How severe is CVE-2021-27561?
Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-27561 known to be exploited?
Yes. CVE-2021-27561 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.