CRITICAL

CVE-2021-25833

CVSS v3

9.8

CRITICAL

EPSS Score

43.5 %

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-2021-25833 yet.

Full record on NVD

Description

A file extension handling issue was found in [server] module of ONLYOFFICE DocumentServer v4.2.0.71-v5.6.0.21. The file extension is controlled by an attacker through the request data and leads to arbitrary file overwriting. Using this vulnerability, a remote attacker can obtain remote code execution on DocumentServer.

Technical details

Published: 2021-03-01

Frequently asked questions

What is CVE-2021-25833?

Is CVE-2021-25833 actively exploited?

Active exploitation of CVE-2021-25833 has not been confirmed. Its EPSS score was 43.5% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-25833?

CVE-2021-25833 has a CVSS v3 base score of 9.8 (CRITICAL severity).

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