# CVE-2021-39168: TimelockController vulnerability in OpenZeppelin Contracts

> An actor with the executor role in OpenZeppelin TimelockController can escalate privileges, requiring revocation of untrusted executor roles.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Aug 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vrw4-w73r-6mm8

## What is CVE-2021-39168?

CVE-2021-39168 is a critical vulnerability in openzeppelin-contracts-upgradeable, published on 26 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OpenZepplin is a library for smart contract development. In affected versions a vulnerability in TimelockController allowed an actor with the executor role to escalate privileges. Further details about the vulnerability will be disclosed at a later date. As a workaround revoke the executor role from accounts not strictly under the team's control. We recommend revoking all executors that are not also proposers. When applying this mitigation, ensure there is at least one proposer and executor remaining.

Weakness: CWE-269 (Improper Privilege Management)

## Which versions are affected by CVE-2021-39168?

4 open source packages ship an affected version, including @openzeppelin/contracts-upgradeable. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@openzeppelin/contracts-upgradeable` | npm | From 3.3.0 | 3.4.2 |
| `@openzeppelin/contracts-upgradeable` | npm | From 3.3.0 | 3.4.2 |
| `@openzeppelin/contracts-upgradeable` | npm | From 4.0.0 | 4.3.1 |
| `@openzeppelin/contracts-upgradeable` | npm | From 4.0.0 | 4.3.1 |

Products: Openzeppelin Contracts.

## How do I fix CVE-2021-39168?

Upgrade @openzeppelin/contracts-upgradeable to a fixed version for your release line: 3.4.2 or 4.3.1.

## Is CVE-2021-39168 being exploited?

There is no known exploitation of CVE-2021-39168 in the wild and no public exploit code.

## Other vulnerabilities in openzeppelin-contracts-upgradeable

- [CVE-2021-39167](https://insights.sbomify.com/CVE-2021-39167/): TimelockController vulnerability in OpenZeppelin Contracts (critical 10.0)
- [CVE-2021-41264](https://insights.sbomify.com/CVE-2021-41264/): UUPSUpgradeable vulnerability in OpenZeppelin Contracts (critical 9.8)
- [CVE-2022-35961](https://insights.sbomify.com/CVE-2022-35961/): ECDSA signature malleability in OpenZeppelin Contracts (high 7.9)
- [CVE-2022-31198](https://insights.sbomify.com/CVE-2022-31198/): GovernorVotesQuorumFraction updates to quorum may affect past defeated proposals in @openzeppelin/contracts (high 7.5)
- [CVE-2022-31170](https://insights.sbomify.com/CVE-2022-31170/): OpenZeppelin Contracts's ERC165Checker may revert instead of returning false (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-39168 and fix it if it is affected.

What it is: CVE-2021-39168 is a critical vulnerability in openzeppelin-contracts-upgradeable, published on 26 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-39168 in the wild and no public exploit code.

Affected packages and fixed versions:
- @openzeppelin/contracts-upgradeable (npm): affected from 3.3.0; fixed in 3.4.2
- @openzeppelin/contracts-upgradeable (npm): affected from 3.3.0; fixed in 3.4.2
- @openzeppelin/contracts-upgradeable (npm): affected from 4.0.0; fixed in 4.3.1
- @openzeppelin/contracts-upgradeable (npm): affected from 4.0.0; fixed in 4.3.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-39168/ (Markdown: https://insights.sbomify.com/CVE-2021-39168/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-39168
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-39168
- OSV: https://osv.dev/vulnerability/CVE-2021-39168

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-39168/
Summaries are generated and may contain mistakes; the official description above is the record.