CVE-2026-2476 in Plugins
Summary
by MITRE • 03/16/2026
Mattermost Plugins versions <=2.0.3.0 fail to properly mask sensitive configuration values which allows an attacker with access to support packets to obtain original plugin settings via exported configuration data. Mattermost Advisory ID: MMSA-2026-00606
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Analysis
by VulDB Data Team • 03/20/2026
The vulnerability identified as CVE-2026-2476 affects Mattermost Plugins versions 2.0.3.0 and earlier, representing a critical security flaw in the handling of sensitive configuration data. This issue stems from inadequate masking of sensitive parameters within plugin settings, creating a significant risk for organizations relying on Mattermost for secure communications and collaboration. The vulnerability specifically impacts the export functionality of plugin configurations, where sensitive data is not properly obfuscated during the support packet generation process.
The technical flaw manifests in the improper handling of configuration values during the export process, where sensitive information such as API keys, passwords, and authentication tokens are stored in plaintext within the exported data packets. This design oversight allows an attacker with access to support packets to directly extract original plugin settings without requiring additional exploitation techniques. The vulnerability is classified under CWE-200, which addresses improper exposure of sensitive information, and represents a failure in data masking and sanitization practices. The flaw exists because the system does not implement proper redaction mechanisms for sensitive fields during configuration export operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with direct access to critical system credentials and configuration parameters. Organizations using affected Mattermost Plugin versions face potential unauthorized access to integrated services, compromised authentication mechanisms, and exposure of internal system configurations. Attackers could leverage this information to escalate privileges, access additional systems, or conduct further reconnaissance activities. The vulnerability aligns with ATT&CK technique T1552.001, which covers "Unsecured Credentials," and T1078.004, which addresses "Valid Accounts: Cloud Accounts," as the exported credentials could enable unauthorized access to cloud-based services integrated with Mattermost.
Mitigation strategies for this vulnerability require immediate patching of affected Mattermost Plugin versions to 2.0.4.0 or later, which implements proper configuration value masking during export operations. Organizations should also implement additional security controls such as access restrictions on support packet generation, regular monitoring of export activities, and comprehensive credential rotation procedures. Security teams should conduct thorough audits of exported configuration data to identify and remediate any previously compromised sensitive information. The implementation of automated tools to verify proper masking of sensitive values during export processes would further strengthen the security posture. Additionally, organizations should establish strict access controls for support packet generation and maintain detailed logging of all configuration export activities to detect potential unauthorized access attempts.