GHSA-h45m-mgcp-q388

Severity: HIGH

Summary

The TOTP brute-force rate limiter in opensslencryptserver/modules/pepper/totp.py at lines 47-98 uses an in-memory defaultdict(list) as a class variable.

Affected Code

class TOTPRateLimiter:
    def __init__(self, ...):
        self.attempts: Dict[str, List[datetime]] = defaultdict(list)
        self.lockouts: Dict[str, datetime] = {}
class TOTPService:
    _rate_limiter = TOTPRateLimiter()  # Class variable, in-memory only

Impact

1. Rate limit state is not shared across multiple server instances/workers — an attacker can distribute attempts
2. All rate limit state is lost on server restart — allows immediate retry
3. In multi-worker deployments, each worker has independent rate limit state

Recommended Fix

• Use Redis or the database for rate limit state storage
• Or use a shared-memory approach for multi-worker deployments
• At minimum, persist lockout state to survive restarts

Fix

Fixed in commit 2749bc0 on branch releases/1.4.x — added abstract RateLimitBackend with InMemoryBackend and DatabaseBackend implementations; defaults to DatabaseBackend when DB available.