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CVE-2021-25833

CRITICAL
9.8
CVSS Score
Published: March 1, 2021 at 03:09 PM UTC
Updated: June 17, 2026 at 03:42 AM UTC
1 product affected across 1 vendorDocument Server

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Severity
CRITICAL9.8
Exploit prediction
EPSS 44%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Document Server· Onlyoffice
95%
4.2.0.71 ≤ v ≤ 5.6.0.21

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (6)

x_refsource_MISCProductVendor Advisory
Source: [email protected]
https://github.com/ONLYOFFICE/DocumentServer
x_refsource_MISCProduct
Source: [email protected]
https://github.com/ONLYOFFICE/server
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/DocService/sources/converterservice.js#L200
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L283
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L593
x_refsource_MISCExploitThird Party Advisory
Source: [email protected]
https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25833

CVSS

9.8CRITICAL[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-22

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