CVE-2025-2571 in Mattermost
Summary
by MITRE • 05/30/2025
Mattermost versions 10.7.x <= 10.7.0, 10.6.x <= 10.6.2, 10.5.x <= 10.5.3, 9.11.x <= 9.11.12 fail to clear Google OAuth credentials when converting user accounts to bot accounts, allowing attackers to gain unauthorized access to bot accounts via the Google OAuth signup flow.
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Analysis
by VulDB Data Team • 06/08/2025
This vulnerability exists in Mattermost server versions across multiple release branches including 10.7.0, 10.6.2, 10.5.3, and 9.11.12 where the application fails to properly sanitize authentication credentials during user account conversion operations. The flaw specifically impacts the Google OAuth authentication flow when transitioning regular user accounts into bot accounts, creating a persistent security risk that allows unauthorized access through the OAuth signup mechanism. The vulnerability is categorized under CWE-200 as it involves improper handling of sensitive information and represents a credential exposure issue within the authentication system. This weakness enables attackers to exploit the conversion process and maintain access to bot accounts using compromised Google OAuth credentials that should have been invalidated during the account type change.
The technical implementation flaw occurs when Mattermost processes the conversion of user accounts to bot accounts, failing to clear the Google OAuth session data and authentication tokens that were previously associated with the user account. During this conversion process, the system retains the OAuth credentials in memory or database storage, allowing subsequent authentication attempts through the Google OAuth signup flow to succeed even when targeting bot accounts. This represents a critical failure in the privilege management and credential lifecycle handling within the application's authentication subsystem. The vulnerability is particularly concerning because it operates at the authentication boundary where user and bot account types intersect, creating an attack surface that leverages legitimate authentication mechanisms against the system's own access control policies.
The operational impact of this vulnerability extends beyond simple credential theft, as it enables attackers to escalate privileges and gain unauthorized access to bot accounts that are typically designed to operate with restricted permissions and specific security contexts. Bot accounts often serve critical functions within Mattermost environments including automated notifications, integration services, and administrative tasks that require elevated privileges. Attackers can exploit this vulnerability to impersonate legitimate bot accounts and potentially compromise entire communication channels, data integrity, and service availability. The attack vector is particularly effective because it leverages the existing trust relationship established through Google OAuth, making it difficult to detect through standard security monitoring systems that might not flag legitimate OAuth flows as suspicious. This vulnerability aligns with ATT&CK technique T1078.004 which involves legitimate credentials used for unauthorized access and represents a privilege escalation opportunity within the authentication framework.
Mitigation strategies should focus on implementing proper credential cleanup during account conversion operations, ensuring that all OAuth session data and authentication tokens are completely removed when transitioning user accounts to bot accounts. Organizations should implement immediate patching of affected Mattermost versions and consider implementing additional monitoring for account conversion events, particularly those involving OAuth authentication methods. The system should enforce strict credential lifecycle management policies that automatically invalidate all external authentication tokens during account type changes. Security teams should also implement network-level monitoring to detect unusual OAuth authentication patterns and establish automated alerts for suspicious account conversion activities. Additionally, organizations should review their bot account management policies and consider implementing additional authentication layers or access controls that would limit the impact even if this vulnerability were exploited. The vulnerability demonstrates the importance of proper session management and credential sanitization in authentication systems, particularly when transitioning between different account types with varying security requirements.