What is CVE-2021-43447?

CVE-2021-43447 is a high-severity vulnerability in Onlyoffice Server, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2023-01-23.

How severe is CVE-2021-43447?

High severity. CVSS v3 base score is 7.5 out of 10.

Auth bypass in Onlyoffice Server

CVE-2021-43447

ONLYOFFICE all versions as of 2021-11-08 is affected by Incorrect Access Control. An authentication bypass in the document editor allows attackers to edit documents without authentication.

Vulnerability class: Broken Authentication

Published 2023-01-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.013 (68.3th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Onlyoffice Server

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

References

github.com/ONLYOFFICE/server (Third Party Advisory)
www.onlyoffice.com/ (Product, Vendor Advisory)
labs.nettitude.com/blog/exploiting-onlyoffice-web-sockets-for-unauthenticated-r… (Exploit, Third Party Advisory, Mitigation)

Frequently asked questions

What is CVE-2021-43447?: CVE-2021-43447 is a high-severity vulnerability in Onlyoffice Server, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2023-01-23.
How severe is CVE-2021-43447?: High severity. CVSS v3 base score is 7.5 out of 10.