Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2025-66546

17
FAUCET Score

CVE-2025-66546 describes a low-severity vulnerability in Nextcloud Calendar versions prior to 4.7.19, 5.5.6, and 6.0.1, where an attacker could blindly book appointments by guessing sequential IDs without needing an appointment token. This local attack (AV:L) has low complexity (AC:L) and requires low privileges (PR:L), potentially leading to a low impact on confidentiality (C:L) but no impact on integrity or availability. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.0.0, < 4.7.19CPE matchmatch criteria
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*
>= 5.0.0, < 5.5.6CPE matchmatch criteria
cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*
6.0.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:calendar:6.0.0:-:*:*:*:*:*:*
6.0.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:calendar:6.0.0:rc1:*:*:*:*:*:*
6.0.0CPE matchmatch criteria
cpe:2.3:a:nextcloud:calendar:6.0.0:rc2:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.3LOW

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
1.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.12%
Probability of exploitation in next 30 days
EPSS Percentile
2.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0012 is in the 22nd percentile among its peer group of 1,509 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3
Patch
github.com / nextcloud/calendar/pull/7537
Issue Tracking
github.com / nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95
PatchVendor Advisory
hackerone.com / reports/3275810
Issue TrackingVendor Advisory