CVE-2025-3228 in Mattermost
Summary
by MITRE • 06/20/2025
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to properly retrieve requestorInfo from playbooks handler for guest users which allows an attacker access to the playbook run.
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Analysis
by VulDB Data Team • 07/08/2025
The vulnerability identified as CVE-2025-3228 affects Mattermost server versions across multiple release branches including 10.5.x through 10.5.5, 9.11.x through 9.11.15, 10.8.x through 10.8.0, 10.7.x through 10.7.2, and 10.6.x through 10.6.5. This security flaw resides in the playbook handler component of the Mattermost platform, specifically in how the system retrieves requestorInfo for guest users during playbook execution processes. The issue stems from improper access control mechanisms that fail to adequately validate guest user permissions when accessing playbook run information, creating a potential pathway for unauthorized data exposure.
The technical implementation of this vulnerability occurs within the playbook execution handler where the system fails to properly validate or sanitize requestorInfo for guest users. When guest users attempt to access playbook run information through the handler interface, the system does not correctly enforce access restrictions that should normally prevent guest users from viewing sensitive playbook run data. This misconfiguration allows attackers to bypass normal authentication and authorization checks that should normally separate different user roles within the Mattermost environment. The flaw represents a classic access control vulnerability that aligns with CWE-285, which addresses improper authorization within software systems.
From an operational perspective, this vulnerability poses significant risks to organizations using Mattermost for incident response and collaborative workflows. Guest users who should normally have limited access to playbook runs can potentially gain unauthorized access to sensitive information about playbook executions, including run details, participant data, and operational outcomes. This exposure could lead to information disclosure that might reveal organizational processes, security incident handling procedures, or other confidential operational data. The impact is particularly concerning in environments where Mattermost serves as a central platform for security operations and incident response activities.
The vulnerability manifests through the playbook handler's insufficient validation of guest user permissions, creating a persistent access vector that attackers can exploit without requiring elevated privileges. Attackers can leverage this flaw to access playbook run information that should remain restricted to authorized users only, potentially compromising operational security and exposing sensitive workflow details. This weakness directly impacts the principle of least privilege that should govern access to sensitive operational data within collaborative platforms. Organizations should consider this vulnerability in the context of ATT&CK technique T1078 which addresses valid accounts and privilege escalation, as the flaw essentially allows unauthorized access through legitimate user pathways.
Mitigation strategies for CVE-2025-3228 should include immediate deployment of patched Mattermost versions that address the access control validation issue in the playbook handler component. Organizations should also implement additional monitoring of playbook run access patterns to detect anomalous behavior that might indicate exploitation attempts. Network segmentation and access controls should be reviewed to limit exposure of Mattermost instances to untrusted networks. Security teams should conduct comprehensive access control reviews to ensure that guest user permissions are properly enforced and that no unintended access paths exist within the playbook execution framework. Additionally, regular security assessments should verify that proper authentication and authorization mechanisms are functioning as intended across all Mattermost components.