CVE-2026-54639Public exploit

Prototype pollution via malicious token keys

Published Jun 24, 2026 · Updated Jun 24, 2026

Prototype pollution in Style Dictionary 4.3.0 through 5.4.3 allows local users to modify Object.prototype via malicious token keys. convertTokenData strips braces, splits each token key on periods, and assigns the resulting path into a plain object without rejecting proto, so a crafted path writes through the inherited prototype setter. The path is reachable through object-output conversion, enabled Expand API processing, or the transform lifecycle; downstream effects depend on how polluted properties are consumed in a Node.js server, web application, or repository-controlled build.

CVSS severity8.8
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in Style Dictionary 4.3.0 through 5.4.3 allows local users to modify Object.prototype via malicious token keys. convertTokenData strips braces, splits each token key on periods, and assigns the resulting path into a plain object without rejecting proto, so a crafted path writes through the inherited prototype setter. The path is reachable through object-output conversion, enabled Expand API processing, or the transform lifecycle; downstream effects depend on how polluted properties are consumed in a Node.js server, web application, or repository-controlled build.

The record

CVE
CVE-2026-54639
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
Style Dictionary
Product
Style Dictionary
Classifications
CWE-1321
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.3.0, < 5.4.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Style Dictionary · Style Dictionaryversion=>= 4.3.0, < 5.4.4

Published CVSS scores

8.8GitHubCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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