Critical
CVSS 9.1 Broken Authentication Code4rena
Disclosure
Unsigned validity Window Metadata in ERC-4337 Wallet Signature
validUntil/validAfter are appended to userOp.signature but never hashed, so any relayer can alter the validity window without invalidating the signer's ECDSA signature.
- Target
- Ethereum Attestation Protocol
- Category
- Broken Authentication
- Channel
- Code4rena
- Disclosed
- 2026-03
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 Code4rena 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.