CVE-2025-59161 is a vulnerability identified in Element Web, a Matrix protocol web client built using the Matrix React SDK, and also affecting Element Desktop versions prior to 1.11.112. The root cause is improper input validation (CWE-20) related to room predecessor links. Specifically, the application does not sufficiently validate these links, which allows a remote attacker to temporarily replace a legitimate room's entry in the user's room list with an attacker-controlled, unrelated room. This manipulation is impermanent and can be corrected by a user refreshing or reloading the client, which restores the original room list state. The vulnerability does not require any authentication or user interaction to be exploited and can be triggered remotely over the network. The CVSS 4.0 base score is 2.7, indicating a low severity primarily due to the temporary nature of the impact and the lack of direct compromise of confidentiality, integrity, or availability beyond user confusion. The vulnerability could lead to user confusion or misdirection, potentially causing users to act on incorrect assumptions about their communication environment. This could be exploited in social engineering or phishing scenarios within the Matrix ecosystem. The issue has been addressed in Element Web and Desktop version 1.11.112, and users are advised to upgrade to this version or later to mitigate the risk. Since the attack effect is temporary and resolved by a client reload, the impact is limited but still noteworthy in environments where trust and accurate room listings are critical.

For European organizations using Element Web or Desktop clients prior to version 1.11.112, this vulnerability could cause temporary confusion among users by displaying attacker-supplied rooms in place of legitimate ones. While this does not directly compromise sensitive data or system integrity, it could facilitate social engineering attacks or misinformation campaigns within internal or external communications. Organizations relying on Matrix for secure messaging, collaboration, or incident response could see reduced trust in their communication channels during exploitation. The temporary nature of the attack means that availability and data integrity are not permanently affected, but operational disruptions or miscommunications could occur. In regulated sectors such as finance, healthcare, or government, even temporary misinformation could have compliance or reputational consequences. The low CVSS score reflects the limited technical impact, but the human factor risk remains relevant, especially in high-security environments.

1. Immediate upgrade of all Element Web and Desktop clients to version 1.11.112 or later to ensure the patch is applied. 2. Implement user awareness training to recognize potential anomalies in room listings and encourage verification before acting on unexpected room entries. 3. Monitor Matrix client logs and network traffic for unusual room predecessor link activity or unexpected room list changes that could indicate exploitation attempts. 4. Deploy endpoint security solutions capable of detecting anomalous client behavior or unauthorized modifications to client state. 5. Encourage users to perform a manual refresh or reload of the client if suspicious room list behavior is observed, as this action restores the correct state. 6. For organizations with custom Matrix integrations, review and harden input validation logic related to room metadata to prevent similar issues. 7. Maintain an up-to-date inventory of Matrix clients in use across the organization to ensure timely patch management.