CVE-2025-32792 – ses

Package

Manager: npm
Name: ses
Vulnerable Version: >=0 <1.12.0

Severity

Level: High

CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

EPSS: 0.00143 pctl0.3518

Details

ses's global contour bindings leak into Compartment lexical scope ### 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. ### Patches 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`. ### 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/).

Metadata

Created: 2025-04-18T15:10:05Z
Modified: 2025-04-18T18:34:51Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/04/GHSA-h9w6-f932-gq62/GHSA-h9w6-f932-gq62.json
CWE IDs: ["CWE-497"]
Alternative ID: GHSA-h9w6-f932-gq62
Finding: F017
Auto approve: 1