OpenZeppelin Contracts initializer reentrancy may lead to double initialization
Impact
Initializer functions that are invoked separate from contract creation (the most prominent example being minimal proxies) may be reentered if they make an untrusted non-view external call.
Once an initializer has finished running it can never be re-executed. However, an exception put in place to support multiple inheritance made reentrancy possible in the scenario described above, breaking the expectation that there is a single execution.
Note that upgradeable proxies are commonly initialized together with contract creation, where reentrancy is not feasible, so the impact of this issue is believed to be minor.
Patches
A fix is included in the version v4.4.1 of @openzeppelin/contracts and @openzeppelin/contracts-upgradeable.
Workarounds
Avoid untrusted external calls during initialization.
References
https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3006
Credits
This issue was identified and reported by @chaitinblockchain through our bug bounty on Immunefi.
For more information
If you have any questions or comments about this advisory, or need assistance executing the mitigation, email us at security@openzeppelin.com.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @openzeppelin/contracts | >= 3.2.0, < 4.4.1 | 4.4.1 |
| npm package | @openzeppelin/contracts-upgradeable | >= 3.2.0, < 4.4.1 | 4.4.1 |
References
- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-9c22-pwxw-p6hx
- https://nvd.nist.gov/vuln/detail/CVE-2021-46320
- https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3006
- https://github.com/OpenZeppelin/openzeppelin-contracts
- https://github.com/OpenZeppelin/openzeppelin-contracts/releases/tag/v4.4.1
- https://nvd.nist.gov/vuln/detail/CVE-2022-39384
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L- Weakness (CWE)
CWE-665- Platform
- npm
- Package
@openzeppelin/contracts, @openzeppelin/contracts-upgradeable- Disclosed
- 14.12.2021
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-88g8-f5mf-f5rj - CC BY 4.0
OSV / GitHub Advisory Database - GHSA-9c22-pwxw-p6hx - CC BY 4.0
Vulnerability history: @openzeppelin/contracts-upgradeable
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 22
- First → latest
- 08.2021 07.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 3
- High 5
- Medium 12
- Low 2
Disclosures per year
- 2021: 5
- 2022: 8
- 2023: 7
- 2024: 1
- 2025: 1
- 2026: 0
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OpenZeppelin Contracts initializer reentrancy may lead to double initialization this entry
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