CVE-2023-40014: Openzeppelin Contracts

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

OpenZeppelin Contracts is a library for secure smart contract development. Starting in version 4.0.0 and prior to version 4.9.3, contracts using `ERC2771Context` along with a custom trusted forwarder may see `_msgSender` return `address(0)` in calls that originate from the forwarder with calldata shorter than 20 bytes. This combination of circumstances does not appear to be common, in particular it is not the case for `MinimalForwarder` from OpenZeppelin Contracts, or any deployed forwarder the team is aware of, given that the signer address is appended to all calls that originate from these forwarders. The problem has been patched in v4.9.3.

Affected products

• Openzeppelin Openzeppelin Contracts: from 4.0.0, before 4.9.3 (fixed in 4.9.3)
• Openzeppelin Openzeppelin Contracts-Upgradable: from 4.0.0, before 4.9.3 (fixed in 4.9.3)

Published 2023-08-10. Last modified 2026-06-17.