4.8Medium
CVE-2025-66511Nextcloud Calendar app used predictable proposal participant tokens
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.
Weakness (CWE):
CWE-330
Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.
Affected products and versions
| Vendor | Product | Versions | |
|---|---|---|---|
| nextcloud | calendar | 6.0.0 – < 6.0.3 | |
| nextcloud | security-advisories | >= 6.0.0-rc.1, < 6.0.3 |
References and patches
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27 PatchVendor Advisory
- https://github.com/nextcloud/calendar/pull/7659 Issue Tracking
- https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb Patch
- https://hackerone.com/reports/3385434 Vendor Advisory
CPE matches (NVD) (1)
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*≥ 6.0.0 < 6.0.3