CVE-2026-54639
Prototype pollution in Style Dictionary (pre-5.4.4) via tokens data.
Is CVE-2026-54639 being exploited?
Not confirmed. CVE-2026-54639 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-54639?
CVE-2026-54639 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-54639?
Yes. A fix has been recorded for CVE-2026-54639. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-54639 affect?
CVE-2026-54639 affects Style Dictionary (<5.4.4). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-54639?
Upgrade to 5.4.4+; sanitize token data to remove __proto__ keys.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Prototype pollution via token data; can mutate Object.prototype in NodeJS server apps, enabling property injection and logic tampering.
Patch when possible
- affected>= 4.3.0 and < 5.4.4
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.