CVE-2026-54639 Style Dictionary - Prototype Pollution in convertTokenData utility function
Prototype pollution in Style Dictionary allows attackers to manipulate object prototypes, potentially leading to code execution or privilege escalation in Node.js environments.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54639?
CVE-2026-54639 is a high-severity unsafe deserialization vulnerability in style-dictionary, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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__`.
Weakness: CWE-1321
Which versions are affected by CVE-2026-54639?
2 open source packages ship an affected version, including style-dictionary.
| Package | Affected | Fixed in |
|---|---|---|
style-dictionary npm | From 4.3.0 | 5.4.4 |
style-dictionary npm | From 4.3.0 | 5.4.4 |
How do I fix CVE-2026-54639?
Upgrade style-dictionary to 5.4.4 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-54639 being exploited?
There is no known exploitation of CVE-2026-54639 in the wild and no public exploit code.
Sources
Also known as GHSA-vj5c-m527-mpff.