Improper Authorization in Nextcloud Server Affects Calendar Functionality
CVE-2026-45281

8.1HIGH

Key Information:

Vendor

Nextcloud
Status
Security-advisories
Vendor
CVE Published:
1 June 2026

What is CVE-2026-45281?

Nextcloud Server, a widely used open-source content collaboration platform, has a vulnerability that allows authenticated users to potentially access and modify other users' calendars due to insufficient authorization mechanisms. This issue affects multiple versions of the software, making it critical for users to update their installations to the latest versions to ensure their data remains secure.

Affected Version(s)

security-advisories >= 32.0.0, < 32.0.9 < 32.0.0, 32.0.9

security-advisories >= 33.0.0, < 33.0.3 < 33.0.0, 33.0.3

References

https://github.com/nextcloud/security-advisories/security...
x_refsource_CONFIRM
https://github.com/nextcloud/server/pull/59962
x_refsource_MISC
https://hackerone.com/reports/3545964
x_refsource_MISC

CVSS V3.1

Score:
8.1
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.