3.3

CVE-2025-66546: nextcloud calendar

CVSS: 3.3v3.1LowAnalyzed
Published 05-12-2025Last modified 05-12-2025
Open JSON

Vulnerability summary

CVE-2025-66546 is a low (CVSS 3.3) vulnerability in nextcloud calendar. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 2.9% of scored vulnerabilities.

Overall risk
13/100
0100
Low · default modelHow is this calculated?
CVSS score
3.3/10
010
Low · v3.1 (CVE.org)
EPSS score
0.14%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 05-12-2025
    PublishedVulnerability first disclosed.
  2. 05-12-2025
    Last modifiedVulnerability information updated.

Description

Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed blindly booking appointments with a squential ID without known the appointment token. This vulnerability is fixed in 4.7.19, 5.5.6, and 6.0.1.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.14%

Chance of exploitation in the next 30 days

Percentile

3%

Versus all other CVEs

30-day change

0.00 pp

From 0.14% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.14%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Nextcloud2 products
  • calendar≥ 4.0.0, < 4.7.19 | ≥ 5.0.0, < 5.5.6 | 6.0.0 | 6.0.0:rc1 | 6.0.0:rc2 | 6.0.0:rc3 | 6.0.0:rc4 | 6.0.0:rc5 | 6.0.0:rc6
  • security-advisories≥ 6.0.0-rc.1, < 6.0.1 | ≥ 5.0.0-rc.1, < 5.5.6 | ≥ 3.0.0-beta1, < 4.7.19

1 vendor · 2 products

References

4 links