The vulnerability CVE-2026-22775 affects the sveltejs devalue JavaScript library, specifically versions from 5.1.0 up to but not including 5.6.2. Devalue is used to serialize complex JavaScript values into strings when JSON.stringify is insufficient. The root cause is located in the ArrayBuffer hydration process within devalue.parse, which expects input strings to be base64 encoded. However, the library fails to verify this assumption before attempting to decode the input. Maliciously crafted inputs that are not base64 encoded can cause the decoding process to consume excessive CPU cycles and memory resources, resulting in an asymmetric resource consumption or amplification attack. This can lead to denial of service conditions in applications that rely on devalue.parse to process externally supplied data, such as user input or API payloads. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. Although no known exploits are currently reported in the wild, the high CVSS score of 7.5 reflects the significant availability impact. The issue is categorized under CWE-405 (Asymmetric Resource Consumption). The vulnerability was publicly disclosed on January 15, 2026, and fixed in version 5.6.2 of the library. Organizations using affected versions should upgrade promptly to mitigate the risk.

For European organizations, the primary impact of this vulnerability is the risk of denial of service attacks against web applications or services that utilize the vulnerable devalue.parse function on untrusted input. Such DoS attacks can degrade service availability, disrupt business operations, and potentially cause reputational damage. Industries with high reliance on real-time web applications, such as finance, e-commerce, and public services, may experience significant operational interruptions. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely; however, service outages can indirectly affect compliance with regulations like GDPR if service availability commitments are not met. The ease of remote exploitation without authentication increases the threat landscape, especially for publicly accessible applications. Attackers could leverage this vulnerability to amplify resource consumption, potentially overwhelming backend infrastructure or triggering cascading failures in distributed systems.

To mitigate this vulnerability, European organizations should immediately upgrade the sveltejs devalue library to version 5.6.2 or later, where the issue is fixed. Additionally, organizations should audit their codebases to identify all instances where devalue.parse is used on externally supplied data and implement strict input validation and sanitization to ensure only expected base64 encoded strings are processed. Employing rate limiting and resource usage monitoring on endpoints that invoke devalue.parse can help detect and mitigate potential exploitation attempts. Where upgrading is not immediately feasible, consider implementing application-layer firewalls or web application firewalls (WAFs) with custom rules to block suspicious payloads that could trigger excessive resource consumption. Finally, maintain robust logging and alerting mechanisms to quickly identify abnormal CPU or memory usage patterns indicative of exploitation attempts.