CVE-2025-24973 in concorde
Summary
by MITRE • 02/11/2025
Concorde, formerly know as Nexkey, is a fork of the federated microblogging platform Misskey. Prior to version 12.25Q1.1, due to an improper implementation of the logout process, authentication credentials remain in cookies even after a user has explicitly logged out, which may allow an attacker to steal authentication tokens. This could have devastating consequences if a user with admin privileges is (or was) using a shared device. Users who have logged in on a shared device should go to Settings > Security and regenerate their login tokens. Version 12.25Q1.1 fixes the issue. As a workaround, clear cookies and site data in the browser after logging out.
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Analysis
by VulDB Data Team • 02/11/2025
The vulnerability described in CVE-2025-24973 affects Concorde, a federated microblogging platform that originated as a fork of Misskey. This security flaw represents a critical authentication bypass issue that undermines the fundamental security principles of session management and credential handling. The vulnerability specifically targets the logout functionality, which is a core component of any secure web application's authentication system. When users perform a logout operation, the application should immediately invalidate all active sessions and remove any stored authentication tokens from the client-side storage mechanisms. However, in affected versions of Concorde, this critical cleanup process fails to properly remove authentication credentials from browser cookies, creating a persistent security risk that can be exploited by malicious actors.
The technical implementation flaw lies in the improper handling of session termination within the application's authentication subsystem. This type of vulnerability is classified under CWE-613, which deals with insufficient session expiration, and more specifically aligns with CWE-384, which addresses session fixation vulnerabilities. The issue demonstrates a fundamental failure in the application's security architecture where the logout process does not effectively clear client-side storage mechanisms that retain authentication tokens. This allows attackers to potentially reuse these stale credentials even after legitimate users have attempted to terminate their sessions, creating a window of opportunity for unauthorized access. The vulnerability is particularly concerning because it affects the core session management functionality that should provide immediate and complete protection against unauthorized access attempts.
The operational impact of this vulnerability extends far beyond simple credential theft, as it creates a significant risk for administrators and privileged users who may be utilizing shared devices. In shared computing environments, the persistence of authentication tokens in browser cookies means that any subsequent user who accesses the device could potentially gain unauthorized access to the previous user's account, especially if that account possessed administrative privileges. This scenario directly maps to ATT&CK technique T1566, which involves credential harvesting through social engineering and session hijacking, and represents a serious escalation path that could lead to complete system compromise. The vulnerability essentially undermines the security boundary that should exist between different users of the same device, creating an attack surface that could be exploited by anyone with physical access to the device or network monitoring capabilities.
The fix implemented in version 12.25Q1.1 addresses the core issue by properly implementing the logout process to ensure that all authentication tokens stored in browser cookies are immediately invalidated and removed upon user logout. This represents a proper session management implementation that aligns with security best practices and industry standards for web application security. The recommended workaround of manually clearing cookies and site data after logout provides a temporary mitigation strategy that essentially forces the browser to remove all stored authentication information, effectively nullifying the vulnerability until the proper fix is applied. Organizations using Concorde should prioritize updating to version 12.25Q1.1 or later, and users who have logged in on shared devices should immediately navigate to Settings > Security and regenerate their login tokens to ensure that any potentially compromised sessions are invalidated. The vulnerability serves as a reminder of the critical importance of proper session management in web applications and the severe consequences that can arise from inadequate implementation of authentication termination processes.