CVE-2023-34459

Published Jun 16, 2023

Last updated a year ago

Overview

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.
Source
security-advisories@github.com
NVD status
Analyzed

Risk scores

CVSS 3.1

Type
Primary
Base score
5.9
Impact score
3.6
Exploitability score
2.2
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-354

Social media

Hype score
Not currently trending

Configurations