CVE-2023-23940
OpenZeppelin Contracts for Cairo is vulnerable to signature validation bypass
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
6.4
OpenZeppelin Contracts for Cairo is vulnerable to signature validation bypass
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
- Record
CVE-2023-23940- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L - Weakness
- CWE-347, CWE-345
- Updated
- 2026-11-02
EUVDEUVD-2023-0188
6.4
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
- Record
EUVD-2023-0188- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-626q-v9j4-mcp4
6.0
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 [email protected]
- Record
GHSA-626q-v9j4-mcp4- CVSS 4.0
- 6.0 Medium
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
NVD
6.4
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
- Record
CVE-2023-23940- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
OSV
6.4
OpenZeppelin Contracts for Cairo is vulnerable to signature validation bypass
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
- Record
CVE-2023-23940- CVSS 3.1
- 6.4 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
OSVGHSA-626q-v9j4-mcp4
6.0
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 [email protected]
- Record
GHSA-626q-v9j4-mcp4- CVSS 4.0
- 6.0 Medium
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-345, CWE-347
- Updated
- 2026-11-02
OSVPYSEC-2023-39 No score
OpenZeppelin Contracts for Cairo is a library for secure smart contract development written in Cairo for StarkNet, a decentralized ZK Rollup. is_valid_eth_signature is missing a call to finalize_keccak after calling verify_eth_signature. 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. The issue has been patched in 0.6.1.
- Record
PYSEC-2023-39- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
openzeppelin-cairo-contractsPyPI |
0.2.0 up to 0.6.1 | 0.6.1 |
openzeppelin-cairo-contractsPyPI |
0.2.0 up to 0.6.1, plus listed versions 0.2.10.3.00.3.10.3.20.4.0 Show 4 moreShow less0.4.0b00.5.00.5.10.6.0 |
0.6.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-23940 is a medium vulnerability (CVSS 6.4) in Openzeppelin Contracts, published February 2, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.22%, the 12th percentile. Fixed in openzeppelin-cairo-contracts 0.6.1.
References
github.com/OpenZeppelin/cairo-contracts/security/advisories/GHSA-626q-v9j4-mcp4
github.com/OpenZeppelin/cairo-contracts/pull/542/commits/6d4cb750478fca2fd916f73297632f899aca9299
nvd.nist.gov/vuln/detail/CVE-2023-23940
github.com/pypa/advisory-database/tree/main/vulns/openzeppelin-cairo-contracts/PYSEC-2023-39.yaml
github.com/advisories/GHSA-626q-v9j4-mcp4
github.com/CVEProject/cvelistV5/tree/main/cves/2023/23xxx/CVE-2023-23940.json
github.com/OpenZeppelin/cairo-contracts