What is CVE-2021-35066?

CVE-2021-35066 is a critical-severity vulnerability in Connectwise Automate, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.8/10. Published 2021-06-21.

How severe is CVE-2021-35066?

Critical severity. CVSS v3 base score is 9.8 out of 10.

XXE in Connectwise Automate

CVE-2021-35066

An XXE vulnerability exists in ConnectWise Automate before 2021.0.6.132.

Vulnerability class: XXE (XML External Entity)

Published 2021-06-21 · last modified 2026-06-17.

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: 0.011 (63.2th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Connectwise Automate

Weakness classification (CWE)

CWE-611 — Improper Restriction of XML External Entity Reference (XXE)

References

www.connectwise.com/company/trust/security-bulletins (Vendor Advisory)
home.connectwise.com/securityBulletin/60cc8c63508a120001cb6e8d (Permissions Required, Vendor Advisory)

Frequently asked questions

What is CVE-2021-35066?: CVE-2021-35066 is a critical-severity vulnerability in Connectwise Automate, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.8/10. Published 2021-06-21.
How severe is CVE-2021-35066?: Critical severity. CVSS v3 base score is 9.8 out of 10.