CVE-2021-25833
9.8
CRITICAL · CVSS 3.1 · EPSS 43.5% (pctl 99)
Patch early
EPSS 43.5% — above the 10% action threshold.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 43.53% — more likely to be exploited than 99% of all CVEs |
| Weakness | CWE-22 |
| On CISA KEV | no |
| Public exploit | none known |
| Published | 2021-03-01 |
| Last modified | 2026-06-17 |
Affected (1)
| Vendor | Product |
|---|---|
| onlyoffice | document server |
References
- https://github.com/ONLYOFFICE/DocumentServer
- https://github.com/ONLYOFFICE/server
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/DocService/sources/converterservice.js#L200
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L283
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L593
- https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25833
- https://github.com/ONLYOFFICE/DocumentServer
- https://github.com/ONLYOFFICE/server
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/DocService/sources/converterservice.js#L200
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L283
- https://github.com/ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js#L593
- https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25833
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