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Improper share updates could result in extended data access (NC-SA-2019-003)

12th April 2019

Risk level: Low

CVSS v3 Base Score: 9.6 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N)

CWE: Improper Access Control - Generic (CWE-284)

HackerOne report: 452854


A bug could expose more data in reshared link shares than intended by the sharer.

Affected Software

  • Nextcloud Server < 15.0.0 (CVE-2020-8121)
  • Nextcloud Server < 14.0.5 (CVE-2020-8121)
  • Nextcloud Server < 13.0.9 (CVE-2020-8121)

Action Taken

The error has been fixed.


It is recommended that all instances are upgraded to Nextcloud 15.0.0, 14.0.5 or 13.0.9.


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

  • Fabian Riechsteiner - recretix systems AG - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.

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