Blueberry HyperVaultRouter — missing asset index check mints shares for any token

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 61477-c-02-missing-asset-index-check-allows-any-token-to-mint-shar. Standalone Foundry PoC and full write-up: 61477-c-02-missing-asset-index-check-allows-any-token-to-mint-shar_exp in the evm-hack-registry mirror.

Vulnerability classes: vuln/logic/wrong-condition · impact/loss-of-funds/direct-drain · check/missing-asset-validation

Reproduction: a self-contained Foundry PoC that compiles & runs in an isolated project with only forge-std — no fork, no RPC, no anvil_state. Full trace: output.txt. PoC: test/61477-c-02-missing-asset-index-check-allows-any-token-to-mint-shar_exp.sol.

AuditVault taxonomy: severity/high · sector/lending · sector/stable · platform/pashov · wrong-condition · wrong-state

Key info#


Impact	HIGH — any unregistered ERC20 mints USDC-priced shares; attacker redeems real USDC
Protocol	Blueberry HyperVaultRouter
Vulnerable code	`deposit`: `assetIndexes[asset]` defaults to 0 == `USDC_SPOT_INDEX`
Bug class	Missing zero-index / unregistered-asset check
Finding	Pashov Audit Group Blueberry 2025-04-30 · #61477 · C-02
Report	Blueberry-security-review_2025-04-30
Source	AuditVault
Status	Audit finding. Reproduced as a standalone local PoC.
Compiler	`^0.8.24` (PoC)

TL;DR#

deposit(asset, amount) looks up assetIndexes[asset] and requires _isAssetSupported.
Unregistered tokens return mapping default 0, and USDC is hardcoded as index 0.
Attacker deposits a worthless ERC20, receives USDC-priced shares, redeems real USDC.

The vulnerable code#

SOLIDITY

uint64 assetIndex_ = assetIndexes[asset];
require(_isAssetSupported(assetIndex_), "COLLATERAL_NOT_SUPPORTED"); // @> VULN
// FIX: require(assetIndex_ != 0 || asset == address(usdc), "not usdc");

Root cause#

The support check treats index 0 as always valid because USDC lives at USDC_SPOT_INDEX = 0. Solidity mappings return 0 for missing keys, so every unknown token is accepted as USDC.

Preconditions#

Router has real USDC deposits (honest TVL).
Attacker can mint/hold any ERC20 and call deposit.

Attack walkthrough#

Alice deposits 100 USDC → 100e18 shares; TVL = 100e18.
Bob deposits 100 worthless RND → check passes (index 0) → 100e18 shares; TVL still 100e18.
Bob redeems 100e18 shares → 50 USDC of Alice's deposit.

Diagrams#

sequenceDiagram participant Alice participant Router as HyperVaultRouter participant Bob Alice->>Router: deposit USDC 100 Note over Router: TVL 100 shares 100 Bob->>Router: deposit junk 100 Note over Router: index default 0 treated as USDC Bob->>Router: redeem 100 shares Router-->>Bob: 50 USDC stolen

Impact#

Share supply inflates without TVL growth. Attackers convert worthless tokens into claims on real USDC, diluting honest depositors by 50% in the PoC.

Sources#

AuditVault finding #61477
Pashov Blueberry security review 2025-04-30
Reduced source: HyperVaultRouter.deposit / _isAssetSupported (Pashov Blueberry 2025-04-30)

Sources & further analysis#

Reproductions & code

Standalone PoC + full trace: 61477-c-02-missing-asset-index-check-allows-any-token-to-mint-shar_exp (evm-hack-registry mirror).
AuditVault finding: 61477-c-02-missing-asset-index-check-allows-any-token-to-mint-shar.

Alerts & third-party analyses

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

These dashboards index community alerts tweets, post-mortems, and independent write-ups. Reach them through the protocol name above to cross-check this reproduction against other analyses.

Source-level debugger — step opcodes and Solidity in sync