OpenZeppelin Contracts TransparentUpgradeableProxy clashing selector calls may not be delegatedGHSA-mx2q-35m2-x2rh
MEDIUMFix: OpenZeppelin/openzeppelin-contracts#4154GHSA-mx2q-35m2-x2rh is a medium-severity (CVSS 5.3) CWE-436 vulnerability in @openzeppelin/contracts. A fix is available for @openzeppelin/contracts — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-mx2q-35m2-x2rh.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@openzeppelin/contractsnpm@openzeppelin/contracts-upgradeablenpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @openzeppelin/contracts | ≥ 3.2.0&&< 4.8.3 | 4.8.3npm install @openzeppelin/contracts@4.8.3 |
| 📦npm | @openzeppelin/contracts-upgradeable | ≥ 3.2.0&&< 4.8.3 | 4.8.3npm install @openzeppelin/contracts-upgradeable@4.8.3 |
Affected Products
contractsopenzeppelincontracts upgradeableopenzeppelinDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @openzeppelin/contracts, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @openzeppelin/contracts to 4.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mx2q-35m2-x2rh is resolved across your whole dependency graph.
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.
Frequently Asked Questions
Is GHSA-mx2q-35m2-x2rh in your dependencies?
Find it across npm, including transitive dependencies.