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GHSA-fg47-3c2x-m2wr

CRITICAL

TimelockController vulnerability in OpenZeppelin Contracts

Also known asCVE-2021-39167
Published
Aug 30, 2021
Updated
Mar 13, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed

EPSS Exploitation Probability

via FIRST.org ↗
1.6%probability of exploitation in next 30 days
Lower Risk72th percentile+1.15%
0.00%0.70%1.39%2.09%0.4%1.6%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

2 pkgs affected
📦@openzeppelin/contracts📦@openzeppelin/contracts

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Impact

A vulnerability in TimelockController allowed an actor with the executor role to take immediate control of the timelock, by resetting the delay to 0 and escalating privileges, thus gaining unrestricted access to assets held in the contract. Instances with the executor role set to "open" allow anyone to use the executor role, thus leaving the timelock at risk of being taken over by an attacker.

Patches

A fix is included in the following releases of @openzeppelin/contracts and @openzeppelin/contracts-upgradeable:

  • 4.3.1
  • 3.4.2
  • 3.4.2-solc-0.7

Deployed instances of TimelockController should be replaced with a fixed version by migrating all assets, ownership, and roles.

Workarounds

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.

References

Post-mortem.

Credits

The issue was identified by an anonymous white hat hacker through Immunefi.

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 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npm@openzeppelin/contracts4.0.0&&< 4.3.14.3.1
📦npm@openzeppelin/contracts3.3.0&&< 3.4.23.4.2

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @openzeppelin/contracts. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update @openzeppelin/contracts to 4.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fg47-3c2x-m2wr is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-fg47-3c2x-m2wr is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-fg47-3c2x-m2wr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact A vulnerability in `TimelockController` allowed an actor with the executor role to take immediate control of the timelock, by resetting the delay to 0 and escalating privileges, thus gaining unrestricted access to assets held in the contract. Instances with the executor role set to "open" allow anyone to use the executor role, thus leaving the timelock at risk of being taken over by an attacker. ### Patches A fix is included in the following releases of `@openzeppelin/contracts` and `@openzeppelin/contracts-upgradeable`: - 4.3.1 - 3.4.2 - 3.4.2-solc-0.7 Deployed instances of `Ti
O3 Security · Impact-Aware SCA

Is GHSA-fg47-3c2x-m2wr in your dependencies?

O3 detects GHSA-fg47-3c2x-m2wr across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.