Vulnerability Description
OpenZeppelin Contracts is a library for smart contract development. Starting in version 4.7.0 and prior to version 4.9.2, when the `verifyMultiProof`, `verifyMultiProofCalldata`, `procesprocessMultiProof`, or `processMultiProofCalldat` functions are in use, it is possible to construct merkle trees that allow forging a valid multiproof for an arbitrary set of leaves. A contract may be vulnerable if it uses multiproofs for verification and the merkle tree that is processed includes a node with value 0 at depth 1 (just under the root). This could happen inadvertedly for balanced trees with 3 leaves or less, if the leaves are not hashed. This could happen deliberately if a malicious tree builder includes such a node in the tree. A contract is not vulnerable if it uses single-leaf proving (`verify`, `verifyCalldata`, `processProof`, or `processProofCalldata`), or if it uses multiproofs with a known tree that has hashed leaves. Standard merkle trees produced or validated with the @openzeppelin/merkle-tree library are safe. The problem has been patched in version 4.9.2. Some workarounds are available. For those using multiproofs: When constructing merkle trees hash the leaves and do not insert empty nodes in your trees. Using the @openzeppelin/merkle-tree package eliminates this issue. Do not accept user-provided merkle roots without reconstructing at least the first level of the tree. Verify the merkle tree structure by reconstructing it from the leaves.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Openzeppelin | Contracts | >= 4.7.0, < 4.9.2 |
| Openzeppelin | Contracts Upgradeable | >= 4.7.0, < 4.9.2 |
Related Weaknesses (CWE)
References
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/4d2383e17186be3e8cPatch
- https://github.com/OpenZeppelin/openzeppelin-contracts/releases/tag/v4.9.2Release Notes
- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-Vendor Advisory
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/4d2383e17186be3e8cPatch
- https://github.com/OpenZeppelin/openzeppelin-contracts/releases/tag/v4.9.2Release Notes
- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-Vendor Advisory
FAQ
What is CVE-2023-34459?
CVE-2023-34459 is a vulnerability with a CVSS score of 5.3 (MEDIUM). OpenZeppelin Contracts is a library for smart contract development. Starting in version 4.7.0 and prior to version 4.9.2, when the `verifyMultiProof`, `verifyMultiProofCalldata`, `procesprocessMultiPr...
How severe is CVE-2023-34459?
CVE-2023-34459 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2023-34459?
Check the references section above for vendor advisories and patch information. Affected products include: Openzeppelin Contracts, Openzeppelin Contracts Upgradeable.