Critical
CVSS 9.1 JWT Issues Private Engagement
Disclosure
JWT Stored in localStorage Exposed to XSS (Token Theft)
JWT access tokens persisted in localStorage are recoverable via any XSS enabling account takeover.
- Target
- European iGaming Platform
- Category
- JWT Issues
- Channel
- Private Engagement
- Disclosed
- 2026-04
Redaction note
Vendor identity withheld.
This finding is documented here as part of MemCyber’s public disclosure record. The vendor has been anonymized to a sector and region descriptor. Full technical detail — including root cause, reproducible proof-of-concept, remediation guidance, and vendor attribution where granted — is available to qualified prospects under NDA.
Coordinated disclosure
How we handled it.
- Reported to the vendor via Private Engagement with a reproducible proof-of-concept.
- Triage + remediation window coordinated with the vendor security team.
- Fix verified before any public reference.
- This record published only after the embargo period closed.