CVE-2021-41193 is a format string vulnerability identified in the wire-avs component of Wire, an open-source messaging platform. Wire-avs is responsible for audio visual signaling within the application. The vulnerability arises from the use of externally-controlled format strings, classified under CWE-134, which allows an attacker to manipulate format specifiers in input strings processed by the application. This flaw exists in versions of wire-avs prior to 7.1.12. Exploiting this vulnerability can lead to a denial of service (DoS) by causing application crashes or, potentially, arbitrary code execution if an attacker carefully crafts input to overwrite memory or control flow. The vulnerability is remotely exploitable, meaning an attacker does not require local access to the system. No authentication or user interaction is explicitly required for exploitation, increasing the risk. The issue was addressed and fixed in wire-avs version 7.1.12. Currently, there are no known public exploits or workarounds, but the nature of the vulnerability means it could be leveraged for impactful attacks if weaponized. The vulnerability affects all deployments using vulnerable versions of wire-avs, which is integrated into the Wire messenger client and server components used for secure communication.

For European organizations, the impact of this vulnerability could be significant, especially for those relying on Wire for secure communications, including enterprises, government agencies, and NGOs. A successful exploit could disrupt communication channels by causing denial of service, impacting operational continuity. More critically, if arbitrary code execution is achieved, attackers could compromise confidentiality and integrity by intercepting or manipulating sensitive communications, potentially leading to data breaches or espionage. Given Wire's positioning as a privacy-focused messenger, exploitation could undermine trust and compliance with data protection regulations such as GDPR. The lack of authentication or user interaction requirements lowers the barrier for attackers, increasing the threat level. Organizations using outdated versions of wire-avs are particularly vulnerable, and the absence of workarounds means patching is the primary defense. The potential for remote exploitation also raises concerns for cloud-hosted or remotely accessed Wire services within European infrastructures.

European organizations should prioritize upgrading wire-avs to version 7.1.12 or later to remediate this vulnerability. Since no workarounds exist, patching is the only effective mitigation. Organizations should audit their environments to identify all instances of wire-avs and verify version compliance. Additionally, implementing network-level protections such as application-layer firewalls or intrusion prevention systems (IPS) that can detect and block anomalous format string patterns may provide interim defense. Monitoring logs for crashes or unusual behavior in Wire clients or servers can help detect exploitation attempts. Organizations should also enforce strict access controls and network segmentation to limit exposure of Wire components to untrusted networks. Regular security assessments and penetration testing focusing on messaging infrastructure can help identify residual risks. Finally, educating users and administrators about the importance of timely updates and secure configuration of communication tools will support ongoing risk reduction.