Share tokens for public calendars disclosed (NC-SA-2017-011)

8th May 2017

Risk level: Medium

CVSS v3 Base Score: 4.3 (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N)

CWE: Information Exposure Through Directory Listing (CWE-548)

HackerOne report: 218876

Description

A logical error caused disclosure of valid share tokens for public calendars. Thus granting an attacker potentially access to publicly shared calendars without knowing the share token.

Affected Software

Nextcloud Server < 11.0.3 (CVE-2017-0894)

Action Taken

The error has been fixed and regression tests been added.

Resolution

It is recommended that all instances are upgraded to Nextcloud 11.0.3.

Acknowledgements

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

Lukas Reschke - Nextcloud GmbH (lukas@nextcloud.com) - Vulnerability discovery and disclosure.

This advisory is licensed CC BY-SA 4.0.

Security Advisory