CVE-2023-34459
Published: 16 June 2023
Summary
CVE-2023-34459 is a medium-severity Improper Validation of Integrity Check Value (CWE-354) vulnerability in Openzeppelin Contracts. Its CVSS base score is 5.3 (Medium).
Operationally, ranked in the top 24.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-1907
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Proper validation of integrity check values is required for reliable tamper detection, directly reducing undetected modification risks.
Requires validation of integrity check values on every resolution response, directly mitigating tampered or corrupted DNS data.
Control mandates proper validation of integrity values (checksums) on prepared data, making flawed validation of those checks ineffective for attackers.
Requires use of proper integrity verification tools, reducing the chance an incorrect check value is accepted.
Requires proper validation of integrity mechanisms, directly mitigating flawed check-value handling.