Summary
Seroval: Code injection through a typed array's own constructor property
seroval writes a typed array as a call to its constructor. In affected versions, the constructor name in the output is read from a property that data on the value can replace, and it is written without checks. A typed array that received properties from untrusted data can then put arbitrary code into the serialized output.
Details
Version 1.6.0 changed how seroval finds the class of an object, so that objects with their own constructor property serialize correctly. Typed arrays still took the constructor name from the value itself, so the name could come from the untrusted property instead of the array's real type.
These functions are affected:
serialize,serializeAsynccrossSerialize,crossSerializeAsync,crossSerializeStream- the
Serializerclass compileJSON
fromJSON and fromCrossJSON are not affected: they only accept the names of the built-in typed arrays. With the compactArrayBufferViews option, the same lookup throws a TypeError instead of writing code.
Workarounds
If you cannot upgrade, do not copy properties from untrusted objects onto typed arrays, or remove an own constructor property from a typed array before serializing it.
Impact
An application is affected only when it serializes a typed array that has an own constructor property set from untrusted data. That requires code that copies properties from untrusted objects onto a typed array. This is unusual, so the severity is rated Low, even though the result is script execution in the page that receives the output.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in 1.6.11. The constructor name now comes from the array's internal type, which properties on the value cannot change. compactArrayBufferViews uses the real type as well.
Frequently Asked Questions
- What is CVE-2026-116583? CVE-2026-116583 is a medium-severity cross-site scripting (XSS) vulnerability in seroval (npm), affecting versions >= 1.6.0, < 1.6.11. It is fixed in 1.6.11. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- Which versions of seroval are affected by CVE-2026-116583? seroval (npm) versions >= 1.6.0, < 1.6.11 is affected.
- Is there a fix for CVE-2026-116583? Yes. CVE-2026-116583 is fixed in 1.6.11. Upgrade to this version or later.
- Is CVE-2026-116583 exploitable, and should I be worried? Whether CVE-2026-116583 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
- What actually determines whether CVE-2026-116583 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.
- How do I fix CVE-2026-116583? Upgrade
serovalto 1.6.11 or later.