Summary
ses's global contour bindings leak into Compartment lexical scope
Workarounds
This problem can be mitigated either by avoiding top-level let, const, or class bindings in <script> tags, which is an existing industry best-practice, or change these to var bindings to be reflected on globalThis, or upgrade ses to version 1.12.0 or greater.
Some bundlers by default transform top-level let, const, and class bindings to var.
Disclosure
This vulnerability was disclosed by @mingijunggrape in the course of their studies at UNIST (Ulsan National Institute of Science and Technology) as a member of the Web Security Lab (https://websec-lab.github.io/).
Impact
Web pages and web extensions using ses and the Compartment API to evaluate third-party code in an isolated execution environment that have also elsewhere used const, let, and class bindings in the top-level scope of a <script> tag will have inadvertently revealed these bindings in the lexical scope of third-party code.
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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This compromise is addressed in ses version 1.12.0. The mechanism for confining third-party code involves a with block and a semi-opaque scope Proxy. The proxy previously revealed any named property to the surrounding lexical scope if it were absent on globalThis, so that the third-party code would receive an informative ReferenceError, relying on the invalid assumption that only properties of globalThis are in the top-level lexical scope. The solution makes the scope proxy fully opaque. Consequently, accessing an unbound free lexical name will produce undefined instead of throwing ReferenceError.
Assigning to an unbound free lexical name will continue to throw a ReferenceError.
Frequently Asked Questions
- What is CVE-2025-32792? CVE-2025-32792 is a high-severity security vulnerability in ses (npm), affecting versions < 1.12.0. It is fixed in 1.12.0.
- Which versions of ses are affected by CVE-2025-32792? ses (npm) versions < 1.12.0 is affected.
- Is there a fix for CVE-2025-32792? Yes. CVE-2025-32792 is fixed in 1.12.0. Upgrade to this version or later.
- Is CVE-2025-32792 exploitable, and should I be worried? Whether CVE-2025-32792 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-2025-32792 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-2025-32792? Upgrade
sesto 1.12.0 or later.