CVE-2022-41904 is a vulnerability identified in the Element iOS client, a popular Matrix protocol-based messaging application used for secure communications. The issue pertains to versions of Element iOS prior to 1.9.7. The vulnerability arises from insufficient user interface (UI) warnings related to encrypted messages using the Megolm encryption protocol. Specifically, when a message event is encrypted but the trustworthiness of the sender's encryption keys cannot be established, the client failed to display appropriate warning shields or indicators. This UI deficiency means that users could be misled into believing that all messages in a chat room are from verified participants, even if a malicious homeserver injects unauthorized messages. Since the Matrix protocol relies on end-to-end encryption and trust verification to ensure message authenticity and confidentiality, this flaw undermines the integrity of the communication. The vulnerability is classified under CWE-357, which concerns insufficient UI warnings for dangerous operations, highlighting that the core issue is a lack of clear user alerts about potentially untrusted content. The problem was addressed and patched in Element iOS version 1.9.7. There are no known workarounds, and no exploits have been reported in the wild to date. The vulnerability does not affect the underlying encryption mechanism but rather the client’s ability to inform users about the trust status of encrypted messages, which could lead to social engineering or misinformation attacks within trusted communication channels.

For European organizations, especially those relying on Element iOS for secure internal or external communications, this vulnerability presents a risk to the integrity and authenticity of messages. Attackers controlling or compromising a homeserver could inject malicious or misleading messages into group chats without users being alerted to the lack of trust verification. This could facilitate misinformation, social engineering, or manipulation campaigns targeting employees or partners. Confidentiality is not directly compromised since the encryption remains intact, but the trust model is weakened, potentially leading to decisions based on falsified information. Sectors with high reliance on secure messaging, such as government agencies, financial institutions, and critical infrastructure operators in Europe, could face reputational damage or operational disruptions if adversaries exploit this flaw. The absence of UI warnings may also erode user confidence in the security of their communications, impacting adoption of secure messaging platforms. Since no known exploits exist, the immediate risk is moderate, but the potential for targeted attacks remains, especially in environments where threat actors have access to or control over Matrix homeservers.

European organizations should prioritize upgrading all Element iOS clients to version 1.9.7 or later to ensure the vulnerability is patched. Network administrators should audit and restrict access to Matrix homeservers, implementing strict authentication and monitoring to prevent unauthorized control or message injection. Organizations should educate users about verifying message authenticity and encourage skepticism of unexpected or unusual messages, especially in group chats. Deploying endpoint detection and response (EDR) solutions capable of monitoring application behavior may help detect anomalous messaging patterns. Additionally, organizations could consider deploying their own trusted Matrix homeservers or using federated servers with strict trust policies to reduce reliance on potentially malicious third-party servers. Regular security assessments of communication infrastructure and integration of secure messaging usage policies into broader cybersecurity frameworks will further mitigate risks. Since no workaround exists, patching remains the primary defense.