What’s Vulnerable › Vulnerabilities

CVE-2026-113349: OpenCATS before 0.10.0 Missing Authorization in Calendar editEvent/deleteEvent

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-20 · updated 2026-10-22
• Weakness: CWE-639

Description

OpenCATS before 0.10.0 contains a missing authorization vulnerability in CalendarUI::onEditEvent() and onDeleteEvent() that allows authenticated users to modify or delete other users' calendar events. Attackers with EDIT or DELETE access can supply arbitrary eventID values to alter or remove any user's events, including non-public ones restricted to their owner.

Affected products

• OpenCATS: before 0.10.0 — fixed in 0.10.0

How to fix

Upgrade to a fixed version: OpenCATS 0.10.0. Check the vendor advisory for mitigations.

References

• https://github.com/opencats/OpenCATS/blob/5781f41814f09493c7ce05b9251b5e09c1aff0cd/lib/Calendar.php#L83-L150
• https://github.com/opencats/OpenCATS/blob/5781f41814f09493c7ce05b9251b5e09c1aff0cd/modules/calendar/CalendarUI.php#L555-L585
• https://github.com/opencats/OpenCATS/blob/5781f41814f09493c7ce05b9251b5e09c1aff0cd/modules/calendar/CalendarUI.php#L690-L712
• https://github.com/opencats/OpenCATS/commit/aa3b414c3672f5010ca26c44192aa8e72d3735bd
• https://github.com/opencats/OpenCATS/issues/720
• https://github.com/opencats/OpenCATS/releases/tag/v0.10.0
• https://www.vulncheck.com/advisories/opencats-before-0.10.0-missing-authorization-in-calendar-editevent-deleteevent

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