CRITICAL

CVE-2021-25830

CVSS v3

9.8

CRITICAL

EPSS Score

11.8 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2021-25830 yet.

Full record on NVD

Description

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.

Technical details

Published: 2021-03-01

Frequently asked questions

What is CVE-2021-25830?

Is CVE-2021-25830 actively exploited?

Active exploitation of CVE-2021-25830 has not been confirmed. Its EPSS score was 11.8% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-25830?

CVE-2021-25830 has a CVSS v3 base score of 9.8 (CRITICAL severity).

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