Megapot — Attacker can steal JackpotTicketNFTs from JackpotBridgeManager

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 64140-h-01-attacker-can-steal-jackpotticketnfts-from-jackpotbridge. Standalone Foundry PoC and full write-up: 64140-h-01-attacker-can-steal-jackpotticketnfts-from-jackpotbridge_exp in the evm-hack-registry mirror.

Reproduction: self-contained Foundry PoC (forge-std only) — no fork. Full trace: output.txt.

AuditVault taxonomy: lang/solidity · platform/code4rena · severity/high · sector/bridge · sector/nft · genome: broken-logic · direct-drain · account-ownership

Key info#


Impact	HIGH — attacker steals custody JackpotTicketNFTs (and drains approved USDC via callback)
Protocol	Megapot
Bug class	User-controlled external call in `_bridgeFunds` after USDC approve
Finding	Code4rena 2025-11-megapot H-01 · #64140
Report	https://code4rena.com/reports/2025-11-megapot
Source	AuditVault
Status	Audit finding — reproduced as a standalone local synthetic
Compiler	`^0.8.24` (PoC)

TL;DR#

_bridgeFunds calls _bridgeDetails.to with attacker-supplied calldata after optionally approving USDC. Pointing to at the ticket NFT and data at safeTransferFrom(bridge → thief, victimId) steals custody NFTs; onERC721Received pulls the approved USDC so the balance check passes.

HARM: victim's ticket NFT moves to the attacker contract; bridge USDC for the claim is drained in the callback.

Root cause#

User-controlled low-level call in _bridgeFunds with no whitelist / RelayTxData validation.

Preconditions#

Bridge holds victim ticket NFTs in custody; attacker has claimable winnings.

Attack walkthrough#

See synthetic test/64140-….sol. Story beats: seed custody → malicious claimWinnings → _bridgeFunds external call → NFT stolen.

Diagrams#

flowchart TD A["Attacker claimWinnings"] --> B["_bridgeFunds"] B --> C["approve USDC to thief"] B --> D["call NFT.safeTransferFrom"] D --> E["onERC721Received pulls USDC"] E --> F["balance check passes"] D --> G["Victim NFT now at thief"]

Impact#

Custody NFTs representing cross-chain tickets/winnings can be stolen by any claimer who supplies a malicious RelayTxData.

Sources#

AuditVault finding
Report: https://code4rena.com/reports/2025-11-megapot
Reduced source provenance: github.com/code-423n4/2025-11-megapot@f0a7297 JackpotBridgeManager.sol

Sources & further analysis#

Reproductions & code

Standalone PoC + full trace: 64140-h-01-attacker-can-steal-jackpotticketnfts-from-jackpotbridge_exp (evm-hack-registry mirror).
AuditVault finding: 64140-h-01-attacker-can-steal-jackpotticketnfts-from-jackpotbridge.

Alerts & third-party analyses

Web3Sec X hacked database: search.
Rekt leaderboard: search.
Solodit incident search: search.

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