OpenZeppelin Contracts contains Improper Verification of Cryptographic Signature
Cause
is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature.
Impact
As a result, any contract using is_valid_eth_signature from the account library (such as the EthAccount preset) is vulnerable to a malicious sequencer. Specifically, the malicious sequencer would be able to bypass signature validation to impersonate an instance of these accounts.
Risk
In order to exploit this vulnerability, it is required to control a sequencer or prover since they're the ones executing the hints, being able to inject incorrect keccak results.
Today StarkWare is the only party running both a prover or a sequencer, greatly reducing the risk of exploit.
Patches
The issue has been patched in 0.6.1.
For more information
If you have any questions or comments about this advisory:
- Open an issue in the Contracts for Cairo repository
- Email us at security@openzeppelin.com
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | openzeppelin-cairo-contracts | >= 0.2.0, < 0.6.1 | 0.6.1 |
References
- https://github.com/OpenZeppelin/cairo-contracts/pull/542/commits/6d4cb750478fca2fd916f73297632f899aca9299
- https://github.com/OpenZeppelin/cairo-contracts/security/advisories/GHSA-626q-v9j4-mcp4
- https://nvd.nist.gov/vuln/detail/CVE-2023-23940
- https://github.com/OpenZeppelin/cairo-contracts
- https://github.com/pypa/advisory-database/tree/main/vulns/openzeppelin-cairo-contracts/PYSEC-2023-39.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-345, CWE-347- Platform
- Python (PyPI)
- Package
openzeppelin-cairo-contracts- Disclosed
- 02.02.2023
- Updated
- 11.10.2026 12:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2023-39 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-626q-v9j4-mcp4 - CC BY 4.0
Vulnerability history: openzeppelin-cairo-contracts
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 07.2022 02.2023
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 0
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