Rounding favors caller

0xB4641064f64E2F3aAffc1b4b4A66BE75c1C81408

0xB4641064f64E2F3aAffc1b4b4A66BE75c1C81408Monad mainnet

Rounding favors the caller: 2 round-trip properties fail EIP-4626's SHOULD guidance (Security Considerations) at block 111,263,642, by at most 14,626 base units, <0.01% of the amount; no MUST sentence failed.

Known to the watcher from a backfill scan in block 111,041,054, 2026-10-06 12:43 UTC. First deposit seen in block 110,391,946. It was not on the hand-made list the board started from.

Request a re-checkRuns the same 30 properties at the latest block and attests the new report.

What failed

RT-redeem-depositEIP-4626 SHOULD
Forge found a counterexample: the round trip ended 14,626 base units in the caller's favor (144,907,523,788,424,795 against 144,907,523,788,410,169).
EIP-4626, Security Considerations: rounding should favor the Vault over its users. That is a SHOULD, not a MUST.
Counterexample: test_RT_redeem_deposit(([0xb81AEf6fd0631D46eb2febFB061e28079968217b, 0x42047e2bc46C9B21026dC1b7f1bcAfCF3d3C99AB, 0x3fD3C599cB6FAa8fc9457204Ef893BF4fe6b98Be, 0x7E70E65b65D7b49E56f543fc8A31dA5c9B87c9c8], [2, 1369157656841231102401257108935390574257794187020225218071974, 144560500807202019203179602574849247868030344220393522583604737, 41910795479], [6254005027521821681153520687112290221130091716374014238787741697417431949, 30191631338, 25238745865040887575332761391163240387629431405940905293927847, 138924220326931133773093813917949229112272586832910858070047], 215578705186788578543004377382873), 50288063115144969489)
RT-withdraw-depositEIP-4626 SHOULD
Forge found a counterexample: the round trip ended 5,209 base units in the caller's favor (56,500,900 against 56,495,691).
EIP-4626, Security Considerations: rounding should favor the Vault over its users. That is a SHOULD, not a MUST.
Counterexample: test_RT_withdraw_deposit(([0x00000000000000000000000000000000000020ae, 0x00000000000000000000000000000000000051EC, 0x0000000000000000000000000000000000003889, 0x0000000000000000000000000000000000004313], [143, 3, 143, 10143], [4921, 65535, 2837, 65535], 6611), 801644042)

Each round trip shown went in the caller's favor by the amount in its counterexample, against EIP-4626's guidance that rounding should favor the vault. That guidance is a SHOULD; no MUST sentence failed, and it is not a claim that funds are at risk.

What the watcher saw

Every event the watcher recorded for this vault, newest first. Each check is a statement about one block; a re-check with the same outcome is recorded here without a new attestation.

07:26:2910-07Regressed
Spec mismatchRounding favors caller
27 pass, 3 fail, 0 inconclusive, 0 not applicable before; 28 pass, 2 fail, 0 inconclusive, 0 not applicable now.
Now failing: RT-redeem-deposit
No longer failing: sf-maxDeposit-honored, sf-maxMint-honored
07:26:2910-07Attested
Attestation #24 on Monad testnet tx 0x4719bd...54a2ba
07:26:2710-07Checked
Rounding favors caller
28 pass, 2 fail, 0 inconclusive, 0 not applicable at block 111,263,642, 1 min. Report
Why: backfill scan.
07:22:3410-07Queued
Waiting for a check: backfill scan.
07:22:3410-07Checked
Rounding favors caller
28 pass, 2 fail, 0 inconclusive, 0 not applicable at block 111,262,847, 1 min. Report
Why: backfill scan.
07:09:5810-07Queued
Waiting for a check: backfill scan.
07:09:5810-07Checked
Rounding favors caller
27 pass, 3 fail, 0 inconclusive, 0 not applicable at block 111,224,893, 2 min. Report
Why: backfill scan.

JSON: this vault's history

All 30 properties

In report order. Bit i is the bit the registry's passedBitmap and failedBitmap use for that property.

Bit	Property	Result	What was found
a16z/erc4626-tests at ac48546, 26 properties: 16 on EIP-4626 MUST sentences, 10 on SHOULD guidance (the round trips and the allowance checks)
0	`asset`test_assetEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: asset() does not revert
1	`totalAssets`test_totalAssetsEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: totalAssets() does not revert
2	`convertToShares`test_convertToSharesEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: convertToShares gives the same result for any caller
3	`convertToAssets`test_convertToAssetsEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: convertToAssets gives the same result for any caller
4	`maxDeposit`test_maxDepositEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: maxDeposit does not revert
5	`previewDeposit`test_previewDepositEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: deposit mints at least the shares previewDeposit quoted
6	`deposit`test_depositEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: deposit moves assets from the caller, credits shares to the receiver and spends allowance
7	`maxMint`test_maxMintEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: maxMint does not revert
8	`previewMint`test_previewMintEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: mint pulls at most the assets previewMint quoted
9	`mint`test_mintEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: mint moves assets from the caller, credits shares to the receiver and spends allowance
10	`maxWithdraw`test_maxWithdrawEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: maxWithdraw does not revert
11	`previewWithdraw`test_previewWithdrawEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw burns at most the shares previewWithdraw quoted
12	`withdraw`test_withdrawEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw burns owner shares, pays the receiver and spends share allowance
13	`withdraw-zero-allowance`test_withdraw_zero_allowanceEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw on behalf of an owner without allowance reverts
14	`maxRedeem`test_maxRedeemEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: maxRedeem does not revert
15	`previewRedeem`test_previewRedeemEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem pays at least the assets previewRedeem quoted
16	`redeem`test_redeemEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem burns owner shares, pays the receiver and spends share allowance
17	`redeem-zero-allowance`test_redeem_zero_allowanceEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem on behalf of an owner without allowance reverts
18	`RT-deposit-redeem`test_RT_deposit_redeemEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem(deposit(a)) returns no more than a
19	`RT-deposit-withdraw`test_RT_deposit_withdrawEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw(a) burns at least the shares deposit(a) minted
20	`RT-redeem-deposit`test_RT_redeem_depositEIP-4626 SHOULD	Fail	Forge found a counterexample: the round trip ended 14,626 base units in the caller's favor (144,907,523,788,424,795 against 144,907,523,788,410,169). EIP-4626, Security Considerations: rounding should favor the Vault over its users. That is a SHOULD, not a MUST. Checks: deposit(redeem(s)) mints no more than s Raw result reason: Error: a <=~ b not satisfied [uint]; deposit reverted below maxDeposit 2 times (inputs discarded, EIP-4626 says it must not revert) runs: 9 call: test_RT_redeem_deposit(([0xb81AEf6fd0631D46eb2febFB061e28079968217b, 0x42047e2bc46C9B21026dC1b7f1bcAfCF3d3C99AB, 0x3fD3C599cB6FAa8fc9457204Ef893BF4fe6b98Be, 0x7E70E65b65D7b49E56f543fc8A31dA5c9B87c9c8], [2, 1369157656841231102401257108935390574257794187020225218071974, 144560500807202019203179602574849247868030344220393522583604737, 41910795479], [6254005027521821681153520687112290221130091716374014238787741697417431949, 30191631338, 25238745865040887575332761391163240387629431405940905293927847, 138924220326931133773093813917949229112272586832910858070047], 215578705186788578543004377382873), 50288063115144969489) calldata: 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 log: Error: a <=~ b not satisfied [uint] log: Value a: 144907523788424795 log: Value b: 144907523788410169 log: Max Delta: 0 log: Delta: 14626
21	`RT-redeem-mint`test_RT_redeem_mintEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: mint(s) costs at least the assets redeem(s) paid
22	`RT-mint-withdraw`test_RT_mint_withdrawEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw(mint(s)) burns at least s shares
23	`RT-mint-redeem`test_RT_mint_redeemEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem(s) pays no more than mint(s) cost
24	`RT-withdraw-mint`test_RT_withdraw_mintEIP-4626 SHOULD	Pass	No counterexample in 16 fuzz runs at this block. Checks: mint(withdraw(a)) costs at least a
25	`RT-withdraw-deposit`test_RT_withdraw_depositEIP-4626 SHOULD	Fail	Forge found a counterexample: the round trip ended 5,209 base units in the caller's favor (56,500,900 against 56,495,691). EIP-4626, Security Considerations: rounding should favor the Vault over its users. That is a SHOULD, not a MUST. Checks: deposit(a) mints no more than the shares withdraw(a) burned Raw result reason: Error: a <=~ b not satisfied [uint]; deposit reverted below maxDeposit 1 times (inputs discarded, EIP-4626 says it must not revert) runs: 4 call: test_RT_withdraw_deposit(([0x00000000000000000000000000000000000020ae, 0x00000000000000000000000000000000000051EC, 0x0000000000000000000000000000000000003889, 0x0000000000000000000000000000000000004313], [143, 3, 143, 10143], [4921, 65535, 2837, 65535], 6611), 801644042) calldata: 0xfbdc418900000000000000000000000000000000000000000000000000000000000020ae00000000000000000000000000000000000000000000000000000000000051ec00000000000000000000000000000000000000000000000000000000000038890000000000000000000000000000000000000000000000000000000000004313000000000000000000000000000000000000000000000000000000000000008f0000000000000000000000000000000000000000000000000000000000000003000000000000000000000000000000000000000000000000000000000000008f000000000000000000000000000000000000000000000000000000000000279f0000000000000000000000000000000000000000000000000000000000001339000000000000000000000000000000000000000000000000000000000000ffff0000000000000000000000000000000000000000000000000000000000000b15000000000000000000000000000000000000000000000000000000000000ffff00000000000000000000000000000000000000000000000000000000000019d3000000000000000000000000000000000000000000000000000000002fc81e0a log: Error: a <=~ b not satisfied [uint] log: Value a: 56500900 log: Value b: 56495691 log: Max Delta: 0 log: Delta: 5209
Specfirst max-honored properties, MIT, each on one EIP-4626 MUST sentence about a max function
26	`sf-maxDeposit-honored`test_sf_maxDeposit_honoredEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. 1 amounts below the bound were refused; the bound itself was accepted. Checks: deposit goes through up to min(maxDeposit, 1e6 tokens); when a smaller amount is refused the bound must go through, and refusals are counted (EIP-4626: maxDeposit MUST NOT be higher than what deposit accepts)
27	`sf-maxMint-honored`test_sf_maxMint_honoredEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. 19 amounts below the bound were refused; the bound itself was accepted. Checks: mint goes through up to min(maxMint, shares of 1e6 tokens); when a smaller amount is refused the bound must go through, and refusals are counted (EIP-4626: maxMint MUST NOT be higher than what mint accepts)
28	`sf-maxWithdraw-honored`test_sf_maxWithdraw_honoredEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: withdraw goes through up to maxWithdraw; when a smaller amount is refused maxWithdraw must go through, and refusals are counted (EIP-4626: maxWithdraw MUST NOT be higher than what withdraw accepts, and MUST be 0 when withdrawals are disabled)
29	`sf-maxRedeem-honored`test_sf_maxRedeem_honoredEIP-4626 MUST	Pass	No counterexample in 16 fuzz runs at this block. Checks: redeem goes through up to maxRedeem; when a smaller amount is refused maxRedeem must go through, and refusals are counted (EIP-4626: maxRedeem MUST NOT be higher than what redeem accepts, and MUST be 0 when redemptions are disabled)

Onchain attestation

Attestation #24 Valid

It records this exact report: the reportHash stored onchain equals the hash of the report on this page.

isCompliant is false: the attested report has failing, inconclusive or not applicable properties.

Issued: 2026-10-07 07:26 UTC
Issuer: 0x02Bc...5488
Counts: 28 pass, 2 fail, 0 inconclusive, 0 n/a
reportHash: 0x195b2f...8d2049
suiteHash: 0x67de68...c66d91
Transaction: not recorded here; look for Attested id 24 in the registry's logs
Registry: 0x3754...daF7

Report at the attested reportURI

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Replay this check

specfirst check 0xB4641064f64E2F3aAffc1b4b4A66BE75c1C81408 \
  --standard erc4626 \
  --block 111263642 \
  --runs 16 \
  --seed 0xfd8ac3fe9815ce8290b63a34ca72a7c6ec9981ea221a12fff08d14f348ae0cea

Same block, runs and seed. The CLI draws a fresh random sender each run; the seed also salts the 16-user pool.

Report JSON

reportHash 0x195b2f...8d2049 is keccak256 of the report's canonical JSON (RFC 8785), the value the registry stores.

Badge and API

The badge and the JSON read the registry when they are loaded, so they follow new attestations without a rebuild.

[![Specfirst ERC-4626 check](/badge/check/143/0xb4641064f64e2f3aaffc1b4b4a66be75c1c81408.svg)](/v/143/0xb4641064f64e2f3aaffc1b4b4a66be75c1c81408)

JSON API Badge SVG

Implementation

Proxy: Not a proxy
Implementation key: 0x140337825a98fab6300d132d6ee79d34e27baeb2953e007924869fea613f8d35
Key from: The vault's own code: same compiler metadata and same code with immutables masked
Code hash: 0xe91e7caeab2e57992c75e74a14053bb9acd32a2d17160effc35a835ff9f72ea6
Code size: 12,041 bytes
Same key: No other vault on this board

Run

Block: 111,263,642, Monad mainnet
Seed: 0xfd8ac3fe9815ce8290b63a34ca72a7c6ec9981ea221a12fff08d14f348ae0cea
Sender: 0x2f2C3b718Aa819C81E86eBe0a7673b6E2e7bF7b7
Runs: 16 per property
Delta: 0 base units
Forge: forge Version: 1.5.1-Homebrew
forge-std: bf647bd6046f
Reject limit: 4096
Harness: 0xf5d1ee...8d0262
sf properties: 0x1d721e...dfa233
suiteHash: 0x67de68...c66d91
Started: 2026-10-07 07:25 UTC, 73 s
Report: schemaVersion 4