CVE-2023-30541: TransparentUpgradeableProxy clashing selector calls may not be delegated in @openzeppelin/contracts

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-04-17 · updated 2026-06-17
Weakness: CWE-436

Description

OpenZeppelin Contracts is a library for secure smart contract development. A function in the implementation contract may be inaccessible if its selector clashes with one of the proxy's own selectors. Specifically, if the clashing function has a different signature with incompatible ABI encoding, the proxy could revert while attempting to decode the arguments from calldata. The probability of an accidental clash is negligible, but one could be caused deliberately and could cause a reduction in availability. The issue has been fixed in version 4.8.3. As a workaround if a function appears to be inaccessible for this reason, it may be possible to craft the calldata such that ABI decoding does not fail at the proxy and the function is properly proxied through.

Affected products

openzeppelin-contracts: from 3.2.0 before 4.8.3 — fixed in 4.8.3
OpenZeppelin Contracts Upgradeable: from 3.2.0 before 4.8.3 — fixed in 4.8.3

How to fix

Upgrade to a fixed version: openzeppelin-contracts 4.8.3; OpenZeppelin Contracts Upgradeable 4.8.3. Check the vendor advisory for mitigations.

References

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