CVE-2021-41264

Name: CVE-2021-41264
Creator: NVD / NIST
Published: 2021-11-12T18:15:07.733+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.44%

Last modified Jun 17, 2026

CVE-2021-41264 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. OpenZeppelin Contracts is a library for smart contract development. In affected versions upgradeable contracts using `UUPSUpgradeable` may be vulnerable to an attack affecting uninitialized implementation contracts. EPSS estimates a 1.44% chance of exploitation in the next 30 days.

Description

OpenZeppelin Contracts is a library for smart contract development. In affected versions upgradeable contracts using `UUPSUpgradeable` may be vulnerable to an attack affecting uninitialized implementation contracts. A fix is included in version 4.3.2 of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`. For users unable to upgrade; 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).

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.44%

69.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-665

Affected Software

Vendor	Product	Versions
Openzeppelin	Contracts	>= 4.1.0, < 4.3.2

References

https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301Issue Tracking, Mitigation, Patch, Vendor Advisory
https://github.com/OpenZeppelin/openzeppelin-contracts/commit/024cc50df478d2e8f78539819749e94d6df60592Patch, Third Party Advisory
https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-5vp3-v4hc-gx76Third Party Advisory
https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301Issue Tracking, Mitigation, Patch, Vendor Advisory
https://github.com/OpenZeppelin/openzeppelin-contracts/commit/024cc50df478d2e8f78539819749e94d6df60592Patch, Third Party Advisory
https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-5vp3-v4hc-gx76Third Party Advisory

Timeline

Published: Nov 12, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-41264?

How severe is CVE-2021-41264?

CVE-2021-41264 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.44% probability of exploitation in the next 30 days.

How do I fix CVE-2021-41264?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-41264?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST