CVE-2023-41335 in Synapse
Summary
by MITRE • 09/27/2023
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. When users update their passwords, the new credentials may be briefly held in the server database. While this doesn't grant the server any added capabilities—it already learns the users' passwords as part of the authentication process—it does disrupt the expectation that passwords won't be stored in the database. As a result, these passwords could inadvertently be captured in database backups for a longer duration. These temporarily stored passwords are automatically erased after a 48-hour window. This issue has been addressed in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.
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Analysis
by VulDB Data Team • 04/23/2025
The vulnerability identified as CVE-2023-41335 affects Synapse, an open-source Matrix homeserver developed by the Matrix.org Foundation. This security flaw relates to the handling of user authentication credentials during password update operations within the Matrix communication platform. The issue manifests as a temporary storage of updated passwords in the server's database, creating a window of opportunity for unauthorized access to sensitive authentication data. The vulnerability represents a deviation from expected security practices where user credentials should remain ephemeral during authentication processes, particularly when password changes occur. The affected system maintains these temporary credentials for a specific duration, potentially exposing them to risks associated with database access and backup procedures.
The technical implementation flaw occurs during the password update process where the system temporarily stores new user credentials in the database while the authentication mechanism processes the change. This temporary storage violates security best practices by creating a scenario where sensitive information exists in persistent storage longer than necessary. The vulnerability specifically impacts the database backup procedures, as these temporary credentials could be included in backup files and potentially accessed by unauthorized parties. The system automatically removes these stored credentials after a 48-hour period, but this delay creates a window of exposure that could be exploited by attackers with access to database backups or systems with compromised database access privileges. The issue demonstrates a failure in proper credential handling and temporary data management within the authentication flow.
The operational impact of this vulnerability extends beyond simple credential exposure to encompass broader security implications for Matrix-based communication platforms. Organizations relying on Synapse as their homeserver infrastructure face potential risks of credential compromise if database backups are not properly secured or if unauthorized access to backup systems occurs. The vulnerability affects the fundamental security model of the Matrix protocol where user authentication data should remain protected during and after the authentication process. This flaw could enable attackers to obtain user passwords through database compromise scenarios, potentially allowing unauthorized access to user accounts across the Matrix network. The 48-hour window of exposure represents a significant risk period where credentials could be captured and potentially used for account takeover or other malicious activities.
Security mitigations for this vulnerability involve immediate upgrading to Synapse version 1.93.0, which addresses the temporary credential storage issue. Organizations should implement comprehensive database security measures including access controls, encryption of backup files, and regular monitoring of database access patterns. The fix implemented in version 1.93.0 likely includes improvements to the credential handling process to ensure that temporary passwords are not stored in persistent database structures. Security practitioners should also review their backup procedures to ensure that database backups are properly secured and that access to backup systems is restricted to authorized personnel only. The vulnerability aligns with CWE-204, which addresses improper access control during authentication processes, and represents a failure in proper credential lifecycle management. Additionally, this issue intersects with ATT&CK technique T1078 related to valid accounts and privilege escalation, as compromised credentials could enable attackers to gain unauthorized access to user accounts. Organizations should implement network segmentation, database activity monitoring, and regular security audits to prevent exploitation of this vulnerability while maintaining the integrity of their Matrix-based communication infrastructure.