CVE-2025-21607
📋 TL;DR
The Vyper compiler fails to check success flags when using EcRecover and Identity precompiles, allowing attackers to deliberately cause these calls to fail while letting execution continue with incorrect results. This affects smart contracts written in Vyper that use these precompiles. The impact is limited because failed precompiles leave minimal gas for subsequent execution.
💻 Affected Systems
- Vyper Compiler
📦 What is this software?
Vyper by Vyperlang
⚠️ Risk & Real-World Impact
Worst Case
Smart contracts could produce incorrect execution results or state changes when attackers manipulate precompile failures, potentially leading to financial losses or incorrect contract behavior.
Likely Case
Limited impact due to gas constraints - only simple executions can follow failed precompiles, making sophisticated attacks unlikely in real-world contracts.
If Mitigated
No significant impact if contracts don't rely heavily on these precompiles or have proper gas management and error handling.
🎯 Exploit Status
Exploitation requires understanding of EVM gas mechanics and targeting specific precompile calls. No real-world exploits have been identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.4.1
Vendor Advisory: https://github.com/vyperlang/vyper/security/advisories/GHSA-vgf2-gvx8-xwc3
Restart Required: No
Instructions:
1. Update Vyper compiler to version 0.4.1 or later. 2. Recompile all affected smart contracts with the updated compiler. 3. Redeploy recompiled contracts to blockchain networks.
🔧 Temporary Workarounds
Avoid affected precompiles
allTemporarily avoid using EcRecover (0x1) and Identity (0x4) precompiles in Vyper contracts until patched.
Manual gas management
allImplement explicit gas checks and error handling around precompile calls in contract code.
🧯 If You Can't Patch
- Audit contracts for use of EcRecover and Identity precompiles and implement additional validation
- Implement monitoring for unexpected contract behavior or gas usage patterns
🔍 How to Verify
Check if Vulnerable:
Check Vyper compiler version with 'vyper --version'. If version is below 0.4.1, check if contracts use EcRecover or Identity precompiles.Check Version:
vyper --versionVerify Fix Applied:
Verify compiler version is 0.4.1 or higher and recompile contracts. Test precompile functionality with various gas limits.📡 Detection & Monitoring
Log Indicators:
- Unexpected precompile failures in transaction receipts
- Abnormal gas consumption patterns in contract executions
Network Indicators:
- Transactions targeting contracts with specific gas limits to trigger precompile failures
SIEM Query:
Not applicable - blockchain transactions don't use traditional SIEM systems