CVE-2023-29051 is an improper access control vulnerability identified in Open-Xchange GmbH's OX App Suite, a widely used collaborative software platform. The issue stems from the handling of user-defined OXMF (Open-Xchange Markup Format) templates, which can be leveraged to access a limited portion of the internal Java API of the application. This API access allows unauthorized users to discover and modify the application state, including objects and data related to other users and contexts, effectively breaching confidentiality and integrity boundaries. The vulnerability is exacerbated by the fact that the existing configuration switch designed to disable user-generated templates by default was not functioning correctly, leaving the attack surface exposed. Although no public exploits have been reported, the CVSS 3.1 score of 8.1 (high severity) reflects the ease of exploitation (network attack vector, low complexity, requiring low privileges but no user interaction) and the significant impact on confidentiality and integrity. The vendor has addressed the issue by ensuring the disabling switch works as intended and plans to remove the feature entirely in future product releases. This vulnerability affects all versions of OX App Suite prior to the fix, and organizations relying on this software for email, calendaring, and collaboration are at risk of unauthorized data access and manipulation.

For European organizations, the impact of CVE-2023-29051 can be substantial, especially for those using OX App Suite as a core collaboration and communication platform. Unauthorized access to internal APIs and the ability to modify application state can lead to data breaches involving sensitive user information, disruption of business workflows, and potential compliance violations under GDPR due to unauthorized data access. The integrity of communications and shared documents may be compromised, undermining trust and operational reliability. Since the vulnerability does not require user interaction and can be exploited remotely with low privileges, attackers could leverage it to escalate privileges or pivot within networks. This risk is particularly critical for sectors with stringent data protection requirements such as finance, healthcare, and government institutions across Europe. The absence of known public exploits reduces immediate risk but does not eliminate the threat, especially from targeted attackers or insider threats.

European organizations should immediately verify that their OX App Suite installations have the updated configuration that effectively disables user-generated OXMF templates. If the patch or configuration update is not yet applied, organizations should implement compensating controls such as restricting access to the OX App Suite management interfaces and monitoring for unusual template-related activities. Network segmentation and strict access controls should be enforced to limit exposure. Organizations should also prepare for the eventual removal of this feature by the vendor by planning migration or configuration changes accordingly. Regular audits of user privileges and template usage logs can help detect exploitation attempts. Additionally, organizations should stay informed about vendor updates and apply patches promptly once available. Incident response plans should include scenarios involving unauthorized API access and data modification within OX App Suite.