CVE-2019-20849 in Mattermost Mobile App
Summary
by MITRE
An issue was discovered in Mattermost Mobile Apps before 1.26.0. Cookie data can persist on a device after a logout.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2019-20849 represents a critical session management flaw in the Mattermost mobile applications affecting versions prior to 1.26.0. This issue stems from improper handling of authentication state persistence within the mobile client architecture, creating a scenario where sensitive cookie data remains stored on the device even after users have explicitly logged out of their accounts. The flaw directly impacts the security posture of mobile users who rely on Mattermost for enterprise communication and collaboration, as it violates fundamental principles of secure authentication and session handling.
From a technical perspective, the vulnerability manifests as a failure in the application's cookie management system to properly clear or invalidate stored authentication tokens and session data upon logout operations. This persistence of cookie data creates an attack surface where unauthorized parties could potentially access sensitive information if they gain physical access to the device or if the application is compromised through other attack vectors. The issue aligns with CWE-613, which addresses insufficient session expiration, and represents a classic example of inadequate state management in mobile applications. The flaw is particularly concerning because it operates at the client-side level, where traditional network-based security controls may not be effective.
The operational impact of this vulnerability extends beyond simple data exposure risks. Mobile device compromise scenarios become significantly more dangerous when persistent cookies are present, as they can enable attackers to maintain access to corporate communication channels even after legitimate users have attempted to secure their sessions. This creates a persistent threat vector that undermines the security model of the application and potentially exposes sensitive enterprise communications, user credentials, and organizational data. The vulnerability affects the confidentiality and integrity of user sessions, particularly in environments where mobile devices may be lost, stolen, or accessed by unauthorized individuals. Organizations relying on Mattermost for secure communication face elevated risks of data breaches and unauthorized access to their collaborative platforms.
Mitigation strategies for CVE-2019-20849 should prioritize immediate deployment of Mattermost Mobile Apps version 1.26.0 or later, which contains the necessary patches to properly handle cookie data cleanup during logout operations. Additionally, organizations should implement comprehensive mobile device management policies that include mandatory secure logout procedures, device encryption requirements, and regular security assessments of mobile applications. Security teams should also consider deploying additional monitoring controls to detect unusual access patterns that might indicate unauthorized use of persistent session data. The remediation process should include thorough testing to ensure that all cookie and session data are properly cleared upon logout, and that the application maintains proper state management throughout the authentication lifecycle. Organizations should also review their incident response procedures to account for potential exploitation of this vulnerability and establish protocols for rapid detection and remediation of any unauthorized access attempts.