Vulnerability in Ascensio System Sia / Onlyoffice ownCloud Integration Plugin

CVE-2026-84282

A Server-Side Request Forgery (SSRF) vulnerability exists in the ONLYOFFICE ownCloud Integration plugin version 9.12. The /apps/onlyoffice/ajax/settings/address endpoint does not sufficiently validate the user-supplied Document Server URL before initiating outbound connections. An authenticated administrator can manipulate the document server parameter to cause the ownCloud server to send arbitrary requests to attacker-controlled destinations, including localhost and internal network hosts. This allows internal network reconnaissance and TCP port scanning based on differences in server responses.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (18.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-84282: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

References

Frequently asked questions

What is CVE-2026-84282?
CVE-2026-84282 is a medium-severity vulnerability in Ascensio System Sia / Onlyoffice ownCloud Integration Plugin, classified under CWE-918 SERVER-SIDE REQUEST FORGERY (SSRF). CVSS score: 6.5/10. Published 2026-09-08.
How severe is CVE-2026-84282?
Medium severity. CVSS v3 base score is 6.5 out of 10.