CVE-2019-20865 in Mattermost Server
Summary
by MITRE
An issue was discovered in Mattermost Server before 5.12.0, 5.11.1, 5.10.2, 5.9.2, and 4.10.10. The login page allows CSRF.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2019-20865 represents a critical cross-site request forgery flaw affecting Mattermost Server versions prior to 5.12.0 and several older release branches. This issue resides within the authentication mechanism of the platform, specifically targeting the login page functionality that fails to implement proper anti-CSRF protections. The vulnerability enables attackers to perform unauthorized actions on behalf of authenticated users without their knowledge or consent, fundamentally compromising the security model of the communication platform.
The technical implementation of this CSRF vulnerability stems from the absence of anti-CSRF tokens or similar protective mechanisms on the login page forms. When users access the Mattermost login interface, the system does not validate the origin of authentication requests or enforce token-based validation that would prevent malicious actors from crafting forged requests. This flaw allows attackers to exploit the trust relationship between the web application and legitimate users, enabling them to manipulate the authentication flow through carefully constructed malicious requests that appear to originate from legitimate user sessions.
The operational impact of this vulnerability extends beyond simple unauthorized access attempts, as it provides attackers with a pathway to escalate privileges and potentially gain full administrative control over Mattermost instances. Attackers can leverage this vulnerability to create new user accounts, modify existing user permissions, or even delete critical system data. The consequences are particularly severe for organizations relying on Mattermost for secure communications, as the vulnerability undermines the fundamental security assumptions of the platform's authentication system and could lead to data breaches, unauthorized access to sensitive communications, and potential compliance violations.
Organizations affected by this vulnerability should prioritize immediate remediation through the deployment of patched Mattermost Server versions, specifically 5.12.0 or later releases. The implementation of proper anti-CSRF measures including the use of unique tokens for each session, proper validation of request origins, and the enforcement of same-site cookies should be implemented as part of the security hardening process. Additionally, security teams should conduct thorough assessments of their Mattermost deployments to ensure that all affected versions have been updated and that proper access controls are in place to prevent similar vulnerabilities from emerging in other components of the platform. This vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses, and represents a significant concern for organizations following ATT&CK framework's credential access and privilege escalation tactics.