CVE-2021-41264

CRITICAL9.8EPSS 0.64%

UUPSUpgradeable vulnerability in @openzeppelin/contracts

Published: 9/15/2021Modified: 3/13/2026
Also known as:GHSA-5vp3-v4hc-gx76

Description

### Impact Upgradeable contracts using `UUPSUpgradeable` may be vulnerable to an attack affecting uninitialized implementation contracts. We will update this advisory with more information soon. ### Patches A fix is included in version 4.3.2 of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`. ### Workarounds Initialize implementation contracts using `UUPSUpgradeable` by invoking the initializer function (usually called `initialize`). An example is provided [in the forum](https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301). ### References [Post-mortem](https://forum.openzeppelin.com/t/uupsupgradeable-vulnerability-post-mortem/15680). ### For more information If you have any questions or comments about this advisory, or need assistance executing the mitigation, email us at [email protected].

Affected packages (2)

CVSS scores

SourceVersionSeverityVector
osvCVSS 3.1CRITICAL9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References (5)