Missing Authorization in Group Office - #VU164344
Published: November 10, 2026
Vulnerability identifier: #VU164344
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-862
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to force another user's subscribed calendar to re-sync, destroying locally modified events and temporarily disrupting event availability.
The vulnerability exists due to missing authorization in Group Office's Calendar::reload action when resolving a target calendar through Calendar::findById without checking permissions. A remote user can use calendar-module access to submit a Calendar/reload request with another user's subscribed calendar ID to trigger event deletion and re-import from its stored feed when that feed has changed since the last sync.
Affected software
Group Office
Remediation
Install security update from vendor's website.
Group Office - update to 26.0.58