Unrated severityNVD Advisory· Published Dec 5, 2025· Updated Dec 5, 2025
Nextcloud Calendar app used predictable proposal participant tokens
CVE-2025-66511
Description
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
2- Range: <6.0.3
- nextcloud/security-advisoriesv5Range: >= 6.0.0-rc.1, < 6.0.3
Patches
Vulnerability mechanics
References
4- github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fbmitrex_refsource_MISC
- github.com/nextcloud/calendar/pull/7659mitrex_refsource_MISC
- github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27mitrex_refsource_CONFIRM
- hackerone.com/reports/3385434mitrex_refsource_MISC
News mentions
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