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CVE Vulnerability Details :
CVE-2025-66511
PUBLISHED
More InfoOfficial Page
Assigner-GitHub_M
Assigner Org ID-a0819718-46f1-4df5-94e2-005712e83aaa
View Known Exploited Vulnerability (KEV) details
Published At-05 Dec, 2025 | 16:42
Updated At-05 Dec, 2025 | 16:53
Rejected At-
▼CVE Numbering Authority (CNA)
Nextcloud Calendar app used predictable proposal participant tokens

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.

Affected Products
Vendor
Nextcloud GmbHnextcloud
Product
security-advisories
Versions
Affected
  • >= 6.0.0-rc.1, < 6.0.3
Problem Types
TypeCWE IDDescription
CWECWE-330CWE-330: Use of Insufficiently Random Values
Type: CWE
CWE ID: CWE-330
Description: CWE-330: Use of Insufficiently Random Values
Metrics
VersionBase scoreBase severityVector
3.14.8MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Version: 3.1
Base score: 4.8
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27
x_refsource_CONFIRM
https://github.com/nextcloud/calendar/pull/7659
x_refsource_MISC
https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb
x_refsource_MISC
https://hackerone.com/reports/3385434
x_refsource_MISC
Hyperlink: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27
Resource:
x_refsource_CONFIRM
Hyperlink: https://github.com/nextcloud/calendar/pull/7659
Resource:
x_refsource_MISC
Hyperlink: https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb
Resource:
x_refsource_MISC
Hyperlink: https://hackerone.com/reports/3385434
Resource:
x_refsource_MISC
▼Authorized Data Publishers (ADP)
CISA ADP Vulnrichment
Affected Products
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions
Configurations
Workarounds
Exploits
Credits
Timeline
EventDate
Replaced By
Rejected Reason
References
HyperlinkResource
Details not found