Buffer Access with Incorrect Length Value Affecting vyper package, versions [,0.2.9)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-VYPER-22132607
- published2 Nov 2026
- disclosed21 Oct 2026
- creditUnknown
Introduced: 21 Oct 2026
NewCVE-2021-48019 (opens in a new tab)How to fix?
Upgrade vyper to version 0.2.9 or higher.
Overview
vyper is a Pythonic Smart Contract Language for the EVM.
Affected versions of this package are vulnerable to Buffer Access with Incorrect Length Value via the get_create_forwarder_to_bytecode function in vyper/functions/functions.py, which generated non-ERC-1167-compliant forwarder proxy bytecode. The old bytecode used a hardcoded 0x1000-byte return buffer for delegatecall results rather than dynamically sizing the return data, meaning that return data larger than 0x1000 bytes is silently truncated and return data from failed calls may be incorrectly handled, allowing an attacker to influence the integrity or availability of contract interactions that rely on the forwarder proxy.
Note: This is only exploitable when interacting with the forwarder proxy through a Web3 library or similar tooling that encodes calls automatically, rather than via raw eth_call or eth_sendTransaction.