CVE-2026-41242

protobufjs could execute generated JavaScript code derived from protobuf schema metadata. When loading a crafted JSON descriptor, schema-controlled type names and type references could reach runtime code generation without sufficient validation.

Preconditions

• The application must allow an attacker to control or influence a protobuf definition or JSON descriptor.
• The application must load that definition through protobufjs reflection APIs such as descriptor loading.
• The affected generated-code path must be reached, for example by performing an operation on the loaded type.

Workarounds

Do not load protobuf definitions or JSON descriptors from untrusted sources with affected versions. If untrusted schemas must be accepted, validate or restrict them before loading and run schema processing in an isolated environment.

An attacker who can provide a malicious protobuf definition or JSON descriptor to an application may be able to execute arbitrary JavaScript in the context of the process using protobufjs.

This requires control over the protobuf schema or descriptor being loaded. Applications that only decode messages using trusted, application-defined schemas are not directly affected by this issue.

Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.

CVE-2026-41242 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.0.1, 7.5.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-41242? CVE-2026-41242 is a critical-severity code injection vulnerability in protobufjs (npm), affecting versions >= 8.0.0, < 8.0.1. It is fixed in 8.0.1, 7.5.5. Untrusted input is evaluated as executable code within the application's runtime environment.
2. How severe is CVE-2026-41242? CVE-2026-41242 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of protobufjs are affected by CVE-2026-41242? protobufjs (npm) versions >= 8.0.0, < 8.0.1 is affected.
4. Is there a fix for CVE-2026-41242? Yes. CVE-2026-41242 is fixed in 8.0.1, 7.5.5. Upgrade to this version or later.
5. Is CVE-2026-41242 exploitable, and should I be worried? Whether CVE-2026-41242 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41242 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41242?
   • Upgrade protobufjs to 8.0.1 or later
   • Upgrade protobufjs to 7.5.5 or later