Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for meeting proposals using a hash function, allowing an attacker to compute valid participant tokens, which allowed them to request details and submit dates in meeting proposals. The tokens are not purely random generated. This vulnerability is fixed in 6.0.3.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb Patch
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27 Patch, Vendor Advisory
- https://hackerone.com/reports/3385434 Permissions Required, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 6.5 · nextcloudNVD modified 2026-10-18 14:10
Affected (CPE criteria) 1
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*
References 4
- https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb Patch
- https://github.com/nextcloud/calendar/pull/7659 Issue Tracking
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27 Patch, Vendor Advisory
- https://hackerone.com/reports/3385434 Permissions Required, Vendor Advisory