Vulnerability in Onlyoffice Document Server

CVE-2021-25830

A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.2.0.236-v5.6.4.13. An attacker must request the conversion of the crafted file from DOCT into DOCX format. Using the chain of two other bugs related to improper string handling, an attacker can achieve remote code execution on DocumentServer.

EPSS: 0.118 (95.6th percentile) — read the EPSS interpretation.

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.

Affected products

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-25830?
CVE-2021-25830 is a critical-severity vulnerability in Onlyoffice Document Server. CVSS score: 9.8/10. Published 2021-03-01.
How severe is CVE-2021-25830?
Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-25830 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.