NonceStore: In-memory only, replay after restart

[a6b8]

Classification

• Blocker

Problem

NonceStore is a simple in-memory Set(). On server restart all nonces are lost — an attacker can replay previously signed payments after a restart.

Affected Files

• src/v2/exact/evm/ServerExact.mjs (NonceStore class, lines 16-30)

Expected vs Actual

• Expected: Nonces survive server restarts and are synchronized cluster-wide
• Actual: Nonces only in process memory, lost on restart

Recommendation

Persistent NonceStore (Redis/PostgreSQL) with distributed locking. Keep interface (isUsed, markUsed), make backend swappable.

Severity

CRITICAL