CVE-2022-35923 is a vulnerability classified under CWE-400 (Uncontrolled Resource Consumption) affecting the JavaScript validation library v8n, specifically versions prior to 1.5.1. The issue arises from inefficient regular expression implementations in the `lowercase()` and `uppercase()` functions. These regex patterns exhibit high computational complexity, causing excessive CPU usage when processing crafted input strings. For example, a test input consisting of 'a' followed by repeated 'a' characters and ending with an uppercase 'A' (with 32 leading characters) caused the `lowercase()` function to execute for approximately 29.4 seconds. This behavior can be exploited to trigger a denial of service (DoS) condition by overwhelming the system's resources, leading to application unresponsiveness or crashes. The vulnerability does not require authentication or user interaction beyond supplying the crafted input to the vulnerable functions. There are no known workarounds aside from upgrading to version 1.5.1 or later, where the regex inefficiencies have been addressed. No exploits have been observed in the wild to date, but the potential for DoS attacks remains significant due to the nature of the flaw and the widespread use of v8n in JavaScript validation contexts.

For European organizations, the primary impact of CVE-2022-35923 is the risk of denial of service attacks against web applications or services that utilize the vulnerable v8n library for input validation. Such DoS attacks could degrade service availability, disrupt business operations, and potentially lead to reputational damage if critical customer-facing or internal systems become unresponsive. Organizations relying on v8n in high-traffic or security-sensitive environments may experience amplified effects, especially if the vulnerability is exploited as part of a coordinated attack. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact alone can be significant, particularly for sectors such as finance, e-commerce, healthcare, and public services where uptime is critical. Additionally, the lack of authentication requirements for exploitation means that attackers can potentially trigger the DoS remotely without prior access, increasing the threat surface. The absence of known exploits in the wild suggests limited current risk, but the ease of triggering the issue through crafted input warrants proactive mitigation.

European organizations should prioritize upgrading the v8n library to version 1.5.1 or later to eliminate the inefficient regex patterns causing the vulnerability. Where immediate upgrading is not feasible, organizations should implement input validation and sanitization at higher application layers to detect and block unusually long or repetitive input strings that could trigger the regex inefficiency. Rate limiting and request throttling mechanisms should be enforced to reduce the risk of resource exhaustion from repeated malicious requests. Monitoring application performance metrics and setting alerts for abnormal CPU usage spikes can help detect exploitation attempts early. Additionally, organizations should conduct code audits to identify any other uses of complex regex patterns that may pose similar risks. Incorporating Web Application Firewalls (WAFs) with custom rules to detect and block suspicious input patterns targeting the vulnerable functions can provide an additional protective layer. Finally, maintaining an up-to-date inventory of JavaScript libraries and dependencies will facilitate timely patch management and vulnerability response.