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XSS in Files PDF viewer (NC-SA-2020-019)

18th March 2020

Risk level: Low

CVSS v3 Base Score: 3.5 (AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N)

CWE: Cross-site Scripting (XSS) - Generic (CWE-79)

HackerOne report: 819863


An outdated 3rd party library in the Files PDF viewer for Nextcloud Server 18.0.2 caused a Cross-site scripting vulnerability when opening a malicious PDF.

Affected Software

  • Nextcloud Server < 18.0.3 (CVE-2020-8155)

Action Taken

The error has been fixed.


It is recommended that the Nextcloud Server is upgraded to 18.0.3.


The Nextcloud team thanks the following people for their research and responsible disclosure of the above advisory:

This advisory is licensed CC BY-SA 4.0.

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