Vulnerability · Published Jun 24, 2026 · Assigned by GitHub_M
CVE-2026-54639Style Dictionary - Prototype Pollution in convertTokenData utility function
High 8.8
In plain English
A high-severity prototype pollution in style-dictionary from style-dictionary. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Style Dictionary, a build system for creating cross-platform styles, has a prototype pollution vulnerability starting in version 4.3.0 and prior to version 5.4.4. Impact users have: direct usage of `convertTokenData(tokens, { output: 'object' });`; indirect usage, via using Expand API; and/or indirect usage via SD's transform lifecycle. Impact is high for this when style-dictionary is used as an integration in a NodeJS server application. Impact is moderate for when style-dictionary is used as an integration in a Web application. Impact is low for most common cases where the user of style-dictionary also maintains the tokens, and access is limited via read/write access to the repository/workflows where it is used. A patch has been published in version `5.4.4`. The only known workaround is to sanitize token data first. Whether using DTCG format or old Style Dictionary format, check the token data object recursively for any object keys that include `__proto__`.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | style-dictionary | 5.4.4 | GHSA-vj5c-m527-mpff |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| style-dictionary | style-dictionary | >= 4.3.0, < 5.4.4 |
Weakness: CWE-1321 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/style-dictionary/style-dictionary/security/advisories/GHSA-vj5c-m527-mpff x_refsource_CONFIRM
- https://github.com/style-dictionary/style-dictionary/pull/1702 x_refsource_MISC
- https://github.com/style-dictionary/style-dictionary/commit/209085d9782cfc0783c4d983f3f1bb2c515954ec x_refsource_MISC
- https://github.com/style-dictionary/style-dictionary/commit/23b5e8dda143441f0d6b8e2b4222e2da98058bc5 x_refsource_MISC