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NVD Vulnerability Details :
CVE-2025-66511
Analyzed
More InfoOfficial Page
Source-security-advisories@github.com
View Known Exploited Vulnerability (KEV) details
Published At-05 Dec, 2025 | 17:16
Updated At-10 Dec, 2025 | 16:14

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.

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary3.14.8MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Primary3.16.5MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Type: Secondary
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
Type: Primary
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CPE Matches
Nextcloud GmbH
nextcloud
>>calendar>>Versions from 6.0.0(inclusive) to 6.0.3(exclusive)
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*
Weaknesses
CWE IDTypeSource
CWE-330Primarysecurity-advisories@github.com
CWE ID: CWE-330
Type: Primary
Source: security-advisories@github.com
Evaluator Description
Evaluator Impact

Evaluator Solution

Vendor Statements
References
HyperlinkSourceResource
https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fbsecurity-advisories@github.com
Patch
https://github.com/nextcloud/calendar/pull/7659security-advisories@github.com
Issue Tracking
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27security-advisories@github.com
Patch
Vendor Advisory
https://hackerone.com/reports/3385434security-advisories@github.com
Permissions Required
Vendor Advisory
Hyperlink: https://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb
Source: security-advisories@github.com
Resource:
Patch
Hyperlink: https://github.com/nextcloud/calendar/pull/7659
Source: security-advisories@github.com
Resource:
Issue Tracking
Hyperlink: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27
Source: security-advisories@github.com
Resource:
Patch
Vendor Advisory
Hyperlink: https://hackerone.com/reports/3385434
Source: security-advisories@github.com
Resource:
Permissions Required
Vendor Advisory
Change History
0Changes found
Details not found