What is CVE-2021-43448?

CVE-2021-43448 is a medium-severity vulnerability in Onlyoffice Server, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2023-01-23.

How severe is CVE-2021-43448?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Improper input validation in Onlyoffice Server

CVE-2021-43448

ONLYOFFICE all versions as of 2021-11-08 is vulnerable to Improper Input Validation. A lack of input validation can allow an attacker to spoof the names of users who interact with a document, if the document id is known.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

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

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.010 (61.8th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 62nd percentile — 61.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Onlyoffice Server

Weakness classification (CWE)

CWE-20 — Improper Input Validation

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-2021-43448?: CVE-2021-43448 is a medium-severity vulnerability in Onlyoffice Server, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2023-01-23.
How severe is CVE-2021-43448?: Medium severity. CVSS v3 base score is 5.3 out of 10.