CVE-2026-44293: Prototype Poisoning in protobufjs

The primary impact of CVE-2026-44293 is the potential for remote code execution (RCE). An attacker who can influence the protobuf descriptor loaded by an application using protobufjs can inject arbitrary JavaScript code. This code will execute within the context of the application, granting the attacker control over the affected process. The blast radius depends on the application's privileges and access to sensitive data. For example, if the application runs with elevated privileges or has access to databases or other critical resources, the attacker could gain complete control over the system. This vulnerability shares similarities with prototype pollution attacks, where attackers manipulate the prototype chain to inject malicious properties.

1. Veröffentlicht2026-05-12

The recommended mitigation is to upgrade to a patched version of protobufjs that addresses this vulnerability. Unfortunately, a fixed version is not yet available as of the publication date. Until a patch is released, consider implementing input validation on protobuf descriptors to prevent the use of non-string default values for bytes fields. While not a complete solution, this can reduce the attack surface. Additionally, consider using a Web Application Firewall (WAF) to filter out malicious protobuf descriptors. Monitor application logs for unusual JavaScript execution patterns that might indicate exploitation.