CVE-2022-21667 is a vulnerability identified in soketi, an open-source WebSockets server widely used to facilitate real-time communication in web applications. The flaw arises from improper handling of exceptional conditions (CWE-755) during the processing of POST requests. Specifically, when the server receives a POST request with an empty body, it fails to handle this edge case correctly, leading to an unhandled exception that causes the server to crash. This issue affects all versions of soketi prior to 0.24.1. Notably, the vulnerability can be triggered without authentication and without conforming to the Pusher Protocol, meaning any unauthenticated attacker can send a crafted POST request with an empty body to any endpoint on the server and cause a denial of service (DoS) by crashing the server. There are no known workarounds, and the only remediation is to upgrade to version 0.24.1 or later where the issue is patched. No exploits have been reported in the wild to date, but the simplicity of triggering the crash and the lack of authentication requirements make this vulnerability a significant risk for availability disruption in affected environments.

For European organizations, the primary impact of this vulnerability is on the availability of services relying on soketi for real-time WebSocket communication. Organizations using soketi in customer-facing applications, internal dashboards, or critical communication platforms could experience service outages if an attacker exploits this flaw. This could disrupt business operations, degrade user experience, and potentially lead to financial losses or reputational damage. Since the vulnerability can be exploited remotely without authentication, it increases the attack surface and risk of automated or opportunistic attacks. Although the vulnerability does not directly compromise confidentiality or integrity, the denial of service could be leveraged as part of a broader attack strategy, such as distraction during multi-vector attacks or to disrupt incident response capabilities. European sectors with high reliance on real-time data exchange, such as finance, telecommunications, and public services, may be particularly vulnerable to operational disruptions caused by this flaw.

The definitive mitigation is to upgrade all soketi instances to version 0.24.1 or later, where the vulnerability has been addressed. Organizations should prioritize patching in environments exposed to untrusted networks, especially public-facing servers. In addition to patching, organizations should implement network-level protections such as Web Application Firewalls (WAFs) configured to detect and block anomalous POST requests with empty bodies targeting soketi endpoints. Rate limiting and anomaly detection can help mitigate automated exploitation attempts. Monitoring logs for repeated POST requests with empty bodies can provide early warning of exploitation attempts. For environments where immediate patching is not feasible, isolating soketi servers behind VPNs or restricting access to trusted IP ranges can reduce exposure. Finally, organizations should review their incident response plans to include scenarios involving denial of service against real-time communication infrastructure.