CVE-2026-2461 in Plugins
Summary
by MITRE • 03/16/2026
Mattermost Plugins versions <=11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559
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Analysis
by VulDB Data Team • 03/20/2026
This vulnerability exists within Mattermost Plugins versions 11.3 11.0.3 11.2.2 and 10.10.11.0 where the software fails to properly implement authorization checks when modifying comment blocks. The flaw specifically affects scenarios where users with editor permissions attempt to modify comments that were originally created by other board members. This represents a significant authorization bypass issue that undermines the integrity of collaborative comment systems within the Mattermost platform.
The technical implementation flaw stems from inadequate access control mechanisms that should validate whether a user has proper authorization to modify content they did not originally create. When an attacker with editor permissions attempts to modify another user's comment, the system should verify that the modifying user has explicit permission to alter that specific comment block. However, the current implementation lacks this validation step, allowing unauthorized modifications to occur. This vulnerability is classified as a weakness in authorization controls and can be categorized under CWE-285: Improper Authorization, which specifically addresses situations where systems fail to properly enforce access controls.
The operational impact of this vulnerability is substantial as it enables malicious actors with editor privileges to manipulate collaborative work environments. An attacker could modify, delete, or alter comments created by colleagues, potentially leading to information corruption, misinformation dissemination, or disruption of team collaboration processes. This type of vulnerability directly impacts the integrity and confidentiality of shared workspaces, particularly in environments where multiple users contribute to board discussions and comment threads. The attack pattern aligns with ATT&CK technique T1078.004: Valid Accounts, where adversaries leverage legitimate user permissions to perform unauthorized actions within systems they have access to.
Organizations using affected Mattermost Plugin versions should immediately implement mitigations including updating to patched versions of the software, implementing additional monitoring for comment modification activities, and reviewing user permission assignments to minimize the risk of unauthorized modifications. The vulnerability demonstrates the critical importance of proper access control implementation in collaborative platforms where multiple users interact with shared content. Security teams should also consider implementing audit logging for all comment modification activities to detect potential unauthorized changes. Additionally, administrators should review and restrict editor permissions where possible, ensuring that users with such privileges understand the scope of their modification capabilities and that appropriate least-privilege principles are enforced.