CVE-2026-47428
Vitest Browser Mode XSS can execute JS and steal VITEST_API_TOKEN.
Is CVE-2026-47428 being exploited?
Not confirmed. CVE-2026-47428 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 0.61% probability of exploitation in the next 30 days.
How severe is CVE-2026-47428?
CVE-2026-47428 is rated Critical with a CVSS score of 9.6. 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-2026-47428?
Yes. A fix has been recorded for CVE-2026-47428. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-47428 affect?
CVE-2026-47428 affects Vitest >=4.0.17 and <4.1.6 (4.0.17-4.1.5), Vitest <5.0.0-beta.3 (pre-beta.3). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-47428?
Upgrade to Vitest 4.1.6 or 5.0.0-beta.3; restrict runner URLs and rotate exposed tokens.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Reflected XSS in Vitest Browser Mode lets attackers run JS in the server origin to exfiltrate VITEST_API_TOKEN and make authenticated API calls.
Immediate action required
- affected>= 4.0.17 and < 4.1.6
- affected>= 5.0.0-beta.0 and < 5.0.0-beta.3
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.