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CVE-2023-23940

OpenZeppelin Contracts for Cairo is vulnerable to signature validation bypass

6.4 MediumFix available

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

0.22%Down 0.7 points since Feb 4, 2023
90%50%10%1%

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 MediumCVSS: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 MediumCVSS: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:

Record
GHSA-626q-v9j4-mcp4
CVSS 4.0
6.0 MediumCVSS: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 MediumCVSS: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 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L
CVSS 3.1
5.3 MediumCVSS: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 MediumCVSS: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:

Record
GHSA-626q-v9j4-mcp4
CVSS 4.0
6.0 MediumCVSS: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 MediumCVSS: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

Affected packages
PackageAffectedFixed
openzeppelin-cairo-contracts
PyPI
0.2.0 up to 0.6.1
0.6.1
openzeppelin-cairo-contracts
PyPI
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 less
0.4.0b00.5.00.5.10.6.0
0.6.1

History

History
RecordedChangedSources
first indexedCVE 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

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