EUVD-2025-3998

Comprehensive Technical Analysis of EUVD-2025-3998

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-3998 pertains to an improper implementation of the logout process in Concorde, a fork of the federated microblogging platform Misskey. This flaw allows authentication credentials to remain in cookies even after a user has logged out, potentially enabling an attacker to steal authentication tokens. The severity of this vulnerability is rated with a CVSS Base Score of 9.4, which is considered critical.

CVSS Vector Breakdown:

• Attack Vector (AV): Local (L) - The attacker must have physical or local access to the system.
• Attack Complexity (AC): Low (L) - The attack is straightforward and does not require specialized conditions.
• Privileges Required (PR): None (N) - No privileges are required to exploit the vulnerability.
• User Interaction (UI): None (N) - No user interaction is required for the attack to succeed.
• Scope (S): Changed (C) - The vulnerability affects a different security scope.
• Confidentiality (C): High (H) - The vulnerability has a high impact on confidentiality.
• Integrity (I): High (H) - The vulnerability has a high impact on integrity.
• Availability (A): High (H) - The vulnerability has a high impact on availability.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Shared Device Access: An attacker with physical access to a shared device can exploit the vulnerability by accessing the browser's cookies and stealing authentication tokens.
• Browser Session Hijacking: If an attacker gains access to the browser session data, they can extract the authentication tokens and impersonate the user.

Exploitation Methods:

• Cookie Theft: By accessing the browser's cookie storage, an attacker can retrieve the authentication tokens and use them to authenticate as the user.
• Session Replay: The attacker can replay the stolen session tokens to gain unauthorized access to the user's account.

3. Affected Systems and Software Versions

Affected Systems:

• Concorde (formerly Nexkey) versions prior to 12.25Q1.1.

Software Versions:

• All versions of Concorde before 12.25Q1.1 are vulnerable.

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Clear Cookies and Site Data: Users should clear cookies and site data in the browser after logging out to ensure that no authentication tokens remain.
• Regenerate Login Tokens: Users who have logged in on a shared device should go to Settings > Security and regenerate their login tokens.

Long-Term Mitigation:

• Update to the Latest Version: Upgrade to Concorde version 12.25Q1.1 or later, which includes a fix for the vulnerability.
• Implement Strong Authentication: Use multi-factor authentication (MFA) to add an additional layer of security.
• Regular Security Audits: Conduct regular security audits and vulnerability assessments to identify and mitigate similar issues.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to the European cybersecurity landscape, particularly for organizations and individuals using Concorde on shared devices. The potential for unauthorized access to sensitive information and administrative privileges can lead to data breaches, loss of confidentiality, and potential disruption of services. This underscores the importance of robust security practices and timely updates to mitigate such risks.

6. Technical Details for Security Professionals

Vulnerability Details:

• Cause: Improper implementation of the logout process in Concorde, leading to the persistence of authentication credentials in cookies.
• Impact: Unauthorized access to user accounts, including those with administrative privileges, potentially leading to data breaches and service disruptions.

References:

• GitHub Advisory: GHSA-2369-p2wh-7cc2
• GitHub Commit: 1f6ac9b289906083b132e4f9667a31a60ef83e4e

Aliases:

• CVE-2025-24973

Assigner:

• GitHub_M

ENISA IDs:

• Product: Concorde versions < 12.25Q1.1
• Vendor: nexryai

Conclusion: This vulnerability highlights the critical importance of secure logout processes and the need for regular updates and security audits. Organizations and individuals using Concorde should prioritize updating to the latest version and implementing the recommended mitigation strategies to protect against potential exploitation.