CVE-2026-45281
Description
A flaw was found in Nextcloud Server. An authenticated user, with knowledge of another user's principal URL, could exploit improper authorization controls to gain full access to that user's calendar. This allows the attacker to view and modify the victim's calendar, leading to unauthorized information disclosure and data manipulation.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Access control checks for specific user data or functionality can be bypassed.
Access Control
Technical Impact: Gain Privileges or Assume Identity
Horizontal escalation of privilege is possible (one user can view/modify information of another user).
Access Control
Technical Impact: Gain Privileges or Assume Identity
Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access.
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