# Vault share conversion or rounding breaks entitlement

Conversions, fees or rounding create an unintended claim on assets or an eligible loss under supported token behavior.

**Candidate CWE:** [CWE-682](https://cwe.mitre.org/data/definitions/682.html)

## Test hypothesis

In a local vault, compare ordinary round trips with minimal amounts, zero-supply state, direct donations and mixed supported decimals. Track independent asset/share balances and attacker cost.

## Evidence required

Units, initial supply, exact sequence, fees, rounding direction and bounded victim/protocol loss versus baseline.

## Rule out false positives

Expected rounding dust, unsupported token semantics and unprofitable scenarios without eligible harm do not establish the claimed exploit.

## Playbook and command references

- [Contract state: authorization, callbacks and accounting](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/smart-contract-state.html) — Turn protocol promises into explicit invariants and test realistic local operation sequences with independent accounting.

[Find the associated command snippets](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/commands.html?q=Contract%20state%3A%20authorization%2C%20callbacks%20and%20accounting)

## Referenced by these target playbooks

[Web3 & protocols](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/web3.html) · [OSS & self-hosted](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/oss.html)

## Report checklist

- [ ] Capture the affected version, configuration, identities, and object ownership.
- [ ] Preserve a valid baseline and a negative control.
- [ ] Reproduce the forbidden data access, action, or state change on controlled fixtures.
- [ ] Explain the intended security rule and why the observed behavior violates it.
- [ ] State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.

## Conditional ATT&CK mapping

No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the [mapping guide](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/attack.html).

## Primary references

- [OpenZeppelin ERC-4626](https://docs.openzeppelin.com/contracts/5.x/erc4626)

[Back to the complete vulnerability catalog](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/vulnerabilities.html)