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GHSA-5vp3-v4hc-gx76

CRITICAL

UUPSUpgradeable vulnerability in @openzeppelin/contracts

Also known asCVE-2021-41264
Published
Sep 15, 2021
Updated
Mar 13, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed

EPSS Exploitation Probability

via FIRST.org ↗
1.4%probability of exploitation in next 30 days
Lower Risk70th percentile+0.80%
0.14%0.74%1.34%1.94%0.6%1.4%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

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

@openzeppelin/contractsnpm
1.0Mdownloads / week
@openzeppelin/contracts-upgradeablenpm
250Kdownloads / week

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.

References

Post-mortem.

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/contracts4.1.0&&< 4.3.24.3.2
📦npm@openzeppelin/contracts-upgradeable4.1.0&&< 4.3.24.3.2

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 4.3.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5vp3-v4hc-gx76 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-5vp3-v4hc-gx76 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-5vp3-v4hc-gx76. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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).
O3 Security · Impact-Aware SCA

Is GHSA-5vp3-v4hc-gx76 in your dependencies?

O3 detects GHSA-5vp3-v4hc-gx76 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.