CVE-2023-42443
📋 TL;DR
This vulnerability in Vyper smart contract language allows memory corruption when using specific builtin functions with complex expressions, potentially leading to incorrect contract execution or deployment of malicious bytecode. It affects developers using Vyper 0.3.9 and earlier to create Ethereum smart contracts. The corruption can result in unintended contract behavior or security bypasses.
💻 Affected Systems
- Vyper
📦 What is this software?
Vyper by Vyperlang
⚠️ Risk & Real-World Impact
Worst Case
Attackers could deploy malicious smart contracts that steal funds, manipulate contract logic, or create backdoors in decentralized applications.
Likely Case
Smart contracts may execute incorrectly, leading to financial losses, contract failures, or unintended state changes in blockchain applications.
If Mitigated
With proper workarounds, contracts function normally but require careful coding practices to avoid vulnerable patterns.
🎯 Exploit Status
Exploitation requires understanding of Vyper contract development and specific vulnerable patterns. No public exploits known at publication time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: https://github.com/vyperlang/vyper/security/advisories/GHSA-c647-pxm2-c52w
Restart Required: No
Instructions:
No official patch exists. Monitor Vyper GitHub repository for updates and apply workarounds immediately.
🔧 Temporary Workarounds
Cache Complex Expressions
allCache complex expressions in memory variables before passing them as kwargs to vulnerable builtins (raw_call, create_from_blueprint, create_copy_of).
# Example: Instead of raw_call(target, data=msg.data, value=complex_expression), use:
# cached_value = complex_expression
# raw_call(target, data=msg.data, value=cached_value)
🧯 If You Can't Patch
- Audit all smart contracts for usage of raw_call, create_from_blueprint, and create_copy_of with complex expressions
- Implement additional contract validation and testing to detect memory corruption issues
🔍 How to Verify
Check if Vulnerable:
Review Vyper contract source code for raw_call, create_from_blueprint, or create_copy_of calls with complex expressions in value/gas/salt parameters.Check Version:
vyper --versionVerify Fix Applied:
Verify that complex expressions are cached in memory variables before being passed to vulnerable builtins.📡 Detection & Monitoring
Log Indicators:
- Unexpected contract deployment failures
- Incorrect contract execution results
- Memory access errors in transaction logs
Network Indicators:
- Unusual contract deployment patterns
- Transactions with unexpected calldata
SIEM Query:
Not applicable - this is a smart contract development issue