CVE-2026-23957 is a vulnerability classified under CWE-770, which involves the allocation of resources without limits or throttling, specifically in the lxsmnsyc seroval library. Seroval is a JavaScript serialization/deserialization tool that extends beyond the capabilities of JSON.stringify, allowing complex data structures to be stringified and parsed. In versions 1.4.0 and earlier, the deserialization process can be manipulated by an attacker who overrides encoded array lengths with excessively large values. This manipulation causes the deserialization routine to allocate and process far more resources than intended, significantly increasing processing time and CPU usage. The result is a denial-of-service condition where the affected system becomes unresponsive or severely degraded due to resource exhaustion. The vulnerability is remotely exploitable without requiring authentication or user interaction, making it a critical risk for exposed services using seroval. The issue was addressed in version 1.4.1 by introducing limits or throttling mechanisms during deserialization to prevent excessive resource consumption. No known exploits are currently reported in the wild, but the high CVSS score of 7.5 reflects the potential impact and ease of exploitation. The vulnerability affects any application or service that uses seroval versions below 1.4.1, especially those processing untrusted input over the network.

For European organizations, this vulnerability poses a significant risk to service availability. Organizations using seroval in web applications, APIs, or backend services that handle external input could face denial-of-service attacks that disrupt business operations, degrade user experience, or cause downtime. Critical sectors such as finance, healthcare, telecommunications, and government services that rely on JavaScript-based serialization libraries may experience operational interruptions. The lack of confidentiality or integrity impact means data breaches are unlikely, but the availability impact can lead to financial losses, reputational damage, and regulatory scrutiny, especially under GDPR requirements for service continuity. Additionally, attackers could leverage this vulnerability as part of a larger attack chain to distract or exhaust resources while attempting other exploits. The vulnerability’s remote exploitability and no requirement for authentication increase the attack surface, making it a priority for incident response and patch management teams in Europe.

1. Upgrade all instances of the lxsmnsyc seroval library to version 1.4.1 or later immediately to apply the fix that enforces resource allocation limits during deserialization. 2. Implement strict input validation and sanitization on all data received from untrusted sources before deserialization to prevent manipulation of array lengths or other serialized data fields. 3. Employ runtime monitoring and anomaly detection to identify unusual CPU or memory usage patterns indicative of resource exhaustion attacks during deserialization. 4. Use application-layer rate limiting and network-level protections such as Web Application Firewalls (WAFs) to limit the frequency and volume of requests that could trigger the vulnerability. 5. Conduct regular security audits and code reviews focusing on serialization/deserialization logic to identify and remediate similar resource allocation issues. 6. Develop incident response plans that include detection and mitigation strategies for denial-of-service attacks targeting serialization components. 7. Where feasible, isolate services using seroval in separate containers or virtual machines to limit the blast radius of potential DoS attacks.