Vyper vulnerable to memory corruption in certain builtins utilizing `msize`
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-787 and the CVSS impact.
Summary
Vyper is a Pythonic Smart Contract Language for the Ethereum Virtual Machine (EVM). In version 0.3.9 and prior, under certain conditions, the memory used by the builtins `raw_call`, `create_from_blueprint` and `create_copy_of` can be corrupted. For `raw_call`, the argument buffer of the call can be corrupted, leading to incorrect `calldata` in the sub-context. For `create_from_blueprint` and `create_copy_of`, the buffer for the to-be-deployed bytecode can be corrupted, leading to deploying incorrect bytecode. Each builtin has conditions that must be fulfilled for the corruption to happen. For `raw_call`, the `data` argument of the builtin must be `msg.data` and the `value` or `gas` passed to the builtin must be some complex expression that results in writing to the memory. For `create_copy_of`, the `value` or `salt` passed to the builtin must be some complex expression that results in writing to the memory. For `create_from_blueprint`, either no constructor parameters should be passed to the builtin or `raw_args` should be set to True, and the `value` or `salt` passed to the builtin must be some complex expression that results in writing to the memory. As of time of publication, no patched version exists. The issue is still being investigated, and there might be other cases where the corruption might happen. When the builtin is being called from an `internal` function `F`, the issue is not present provided that the function calling `F` wrote to memory before calling `F`. As a workaround, the complex expressions that are being passed as kwargs to the builtin should be cached in memory prior to the call to the builtin.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| vyperlang | vyper | up to 0.3.9 | — | No fix listed | CNA |
| — | vyper (PyPI) | 0.3.4 to before 0.3.10 | 0.3.10 | Patch available | GHSA-c647-pxm2-c52w |
- vyper Vendorvyperlang Affected up to 0.3.9 Fixed in — No fix listed CNA
- vyper (PyPI) Vendor— Affected 0.3.4 to before 0.3.10 Fixed in 0.3.10 Patch available GHSA-c647-pxm2-c52w
Remediation
- Fix · GHSA-c647-pxm2-c52w vyper (PyPI) Fixed in 0.3.10 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2023-42443
- 2026-10-03 Alias added: GHSA-c647-pxm2-c52w
References
Advisory 2
More vyperlang Vyper vulnerabilities
- TI-2024-16182 Vyper bounds check on built-in `slice()` function can be overflowed CVSS 3.1CRITICAL 9.8
- TI-2024-14992 concat built-in can corrupt memory in vyper CVSS 3.1CRITICAL 9.8
- TI-2024-16184 Vyper array negative index vulnerability CVSS 3.1CRITICAL 9.8
- TI-2022-08657 Integer bounds error in Vyper CVSS 3.1CRITICAL 9.8
- TI-2022-11796 Multiple evaluation of contract address in call in vyper CVSS 3.1HIGH 8.2
- TI-2024-21531 vyper performs double eval of the argument of sqrt CVSS 3.1MEDIUM 5.3
Sources
- CVE-2023-42443 · CVE Program
- CVE-2023-42443 · NVD
- FIRST EPSS
- GHSA-c647-pxm2-c52w · GitHub Advisory Database · CC BY 4.0
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