CVE-2025-27105
📋 TL;DR
This vulnerability in Vyper smart contract language allows out-of-bounds array access when using augmented assignment operators on dynamic arrays. Attackers could potentially write to arbitrary memory locations, leading to contract manipulation or funds theft. All users of Vyper smart contracts on EVM-compatible blockchains are affected.
💻 Affected Systems
- vyper
📦 What is this software?
Vyper by Vyperlang
⚠️ Risk & Real-World Impact
Worst Case
Complete contract compromise allowing theft of all funds, contract logic manipulation, or chain disruption through memory corruption.
Likely Case
Selective fund theft from vulnerable contracts, contract state manipulation, or denial of service through contract failure.
If Mitigated
Limited impact if contracts have additional access controls, but fundamental vulnerability remains in the compiler.
🎯 Exploit Status
Exploitation requires understanding of smart contract structure and vulnerable patterns, but no authentication is needed once a vulnerable contract is deployed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.4.1
Vendor Advisory: https://github.com/vyperlang/vyper/security/advisories/GHSA-4w26-8p97-f4jp
Restart Required: No
Instructions:
1. Check current Vyper version: vyper --version
2. Upgrade to version 0.4.1 or later: pip install --upgrade vyper==0.4.1
3. Recompile all existing contracts with the patched version
4. Redeploy any vulnerable contracts that are currently live
🔧 Temporary Workarounds
No workarounds available
allThe advisory states there are no known workarounds for this vulnerability
🧯 If You Can't Patch
- Audit all deployed contracts for use of augmented assignment operators on dynamic arrays
- Consider migrating funds from vulnerable contracts to newly compiled versions
🔍 How to Verify
Check if Vulnerable:
Check if any contracts use patterns like 'array[index] += expression' where expression might modify the same arrayCheck Version:
vyper --versionVerify Fix Applied:
Verify vyper version is 0.4.1 or higher: vyper --version📡 Detection & Monitoring
Log Indicators:
- Contract execution failures
- Unexpected state changes in contract storage
- Failed bounds check errors
Network Indicators:
- Unusual transaction patterns targeting specific contract functions
- Multiple failed transactions to the same contract
SIEM Query:
Not applicable - blockchain transactions are typically monitored through blockchain explorers and contract monitoring tools