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Improper validation of data passed to JSON encoder (NC-SA-2018-006)

3rd August 2018

Risk level: Medium

CVSS v3 Base Score: 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)

CWE: Improper Input Validation (CWE-20)

HackerOne report: 232347


Improper validation of input allowed an attacker to not have their actions logged to the audit log.

Affected Software

  • Nextcloud Server < 12.0.3 (2018-3776)
  • Nextcloud Server < 11.0.5 (2018-3776)

Action Taken

The error has been fixed.


It is recommended that all instances are upgraded to at least Nextcloud 12.0.3.


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

  • Zhouyuan Yang - Fortinet's FortiGuard Labs - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.

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