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Error message discloses existence of file in write-only share (NC-SA-2017-003)

5th February 2017

Risk level: Low

CVSS v3 Base Score: 3.7 (AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:L)

CWE: Information Exposure Through an Error Message (CWE-209)

HackerOne report: 174524


Due to an error in the application logic an adversary with access to a write-only share may enumerate the names of existing files and subfolders by comparing the exception messages.

Affected Software

  • Nextcloud Server < 10.0.2 (CVE-2017-0885)
  • Nextcloud Server < 9.0.55 (CVE-2017-0885)

Action Taken

The error in the application logic has been addressed.


It is recommended that all instances are upgraded to Nextcloud 9.0.55 or 10.0.2.


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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