Grim Finance

A $30M loss on Fantom in 2021, caused by a reentrancy flaw. Here's what happened, the vulnerability class behind it, and where it stands in ProveWall's re-proof pipeline.

$30Mreported loss

2021year

Fantomchain

Reentrancyvulnerability class

Mechanism — cross-function reentrancy on deposit

◷ In the ProveWall re-proof queue

We have not yet re-executed this exploit on a forked chain. When we do, this page will show a signed, independently replayable receipt — the exploit moving value, and the patched control resisting. Until then this is a factual incident summary, not a proof. No proof, no finding.

What this class of bug is

Reentrancy lets a malicious callback re-enter a function before its state is settled, enabling repeated withdrawals or double-spends against the same balance.

How to read this page. The dollar figure is the publicly reported loss attributed to this incident. A ProveWall re-proof reproduces the vulnerability class/mechanism by execution on a forked chain, with a signed receipt — we say so explicitly only once that execution has passed.

Other reentrancy exploits

Same vulnerability class, re-proven or queued on the wall: Cream Finance · Fei/Rari Fuse · Curve / Vyper reentrancy · The DAO

Want your own contract actually proven — not guessed?

Static tools and LLM auditors ask "is there a check here?" and miss the check that exists but is wrong. OmniGuard Labs runs the exploit on a forked chain and sends you a signed pass/fail receipt. Request a proof-backed audit →

Incident pages summarize public exploits for research; re-proofs execute on a forked chain and every claim is independently verifiable.