CVE-2023-32059
📋 TL;DR
This vulnerability in Vyper smart contract language allows attackers to bypass type checking when calling internal functions with default arguments. The bug causes default arguments to be applied incorrectly (left-to-right instead of right-to-left), potentially leading to unexpected contract behavior or security issues. Anyone using Vyper versions before 0.3.8 for Ethereum smart contract development is affected.
💻 Affected Systems
- Vyper smart contract language
📦 What is this software?
Vyper by Vyperlang
⚠️ Risk & Real-World Impact
Worst Case
Smart contracts could execute unintended logic, potentially leading to loss of funds, unauthorized access, or contract manipulation through type confusion attacks.
Likely Case
Smart contracts may behave unexpectedly when internal functions with default arguments are called, potentially causing logic errors or minor security issues.
If Mitigated
With proper testing and code review, the risk is reduced, but the underlying vulnerability remains until patched.
🎯 Exploit Status
Exploitation requires understanding of Vyper's internal function calls with default arguments and the ability to interact with vulnerable smart contracts.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.3.8
Vendor Advisory: https://github.com/vyperlang/vyper/security/advisories/GHSA-ph9x-4vc9-m39g
Restart Required: No
Instructions:
1. Update Vyper to version 0.3.8 or later using pip: pip install vyper>=0.3.8
2. Recompile all existing smart contracts with the updated version
3. Redeploy any affected contracts to blockchain networks
🔧 Temporary Workarounds
Avoid internal functions with default arguments
allRefactor smart contracts to avoid using internal functions with default arguments until patched
🧯 If You Can't Patch
- Audit all smart contracts for internal function calls with default arguments
- Implement additional validation and testing for contract behavior
🔍 How to Verify
Check if Vulnerable:
Check Vyper version: vyper --version. If version is less than 0.3.8, you are vulnerable.Check Version:
vyper --versionVerify Fix Applied:
Verify vyper --version shows 0.3.8 or higher, and test that internal function calls with default arguments work correctly.📡 Detection & Monitoring
Log Indicators:
- Unusual contract behavior, failed transactions, or unexpected state changes in smart contracts
Network Indicators:
- Unusual transaction patterns to vulnerable contracts
SIEM Query:
Not applicable - this is a development tool vulnerability, not a runtime system vulnerability🔗 References
- https://github.com/vyperlang/vyper/commit/c3e68c302aa6e1429946473769dd1232145822ac
- https://github.com/vyperlang/vyper/security/advisories/GHSA-ph9x-4vc9-m39g
- https://github.com/vyperlang/vyper/commit/c3e68c302aa6e1429946473769dd1232145822ac
- https://github.com/vyperlang/vyper/security/advisories/GHSA-ph9x-4vc9-m39g
