CVE-2024-27094 is a medium-severity (CVSS 6.5) Out-of-bounds Read vulnerability in @openzeppelin/contracts. O3 Security confirms whether CVE-2024-27094 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
OpenZeppelin Contracts base64 encoding may read from potentially dirty memory
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
@openzeppelin/contractsnpm@openzeppelin/contracts-upgradeablenpmDescription
OpenZeppelin Contracts is a library for secure smart contract development. The Base64.encode function encodes a bytes input by iterating over it in chunks of 3 bytes. When this input is not a multiple of 3, the last iteration may read parts of the memory that are beyond the input buffer. The vulnerability is fixed in 5.0.2 and 4.9.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @openzeppelin/contracts | ≥ 4.5.0&&< 4.9.6 | 4.9.6 |
| 📦npm | @openzeppelin/contracts-upgradeable | ≥ 5.0.0-rc.0&&< 5.0.2 | 5.0.2 |
| 📦npm | @openzeppelin/contracts | ≥ 5.0.0-rc.0&&< 5.0.2 | 5.0.2 |
| 📦npm | @openzeppelin/contracts-upgradeable | ≥ 4.5.0&&< 4.9.6 | 4.9.6 |
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update @openzeppelin/contracts to 4.9.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27094 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.
How O3 protects you
O3 pinpoints whether CVE-2024-27094 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 CVE-2024-27094. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-27094 in your dependencies?
O3 detects CVE-2024-27094 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.