What’s Vulnerable › Vulnerabilities
CVE-2024-27094: OpenZeppelin Contracts base64 encoding may read from potentially dirty memory
- Severity: high (CVSS 7.4 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.8% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2024-03-21 · updated 2026-06-17
- Weakness: CWE-125
Description
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 products
- openzeppelin-contracts: from 4.5.0 before 4.9.6; from 5.0.0 before 5.0.2 — fixed in 4.9.6, 5.0.2
- OpenZeppelin Contracts Upgradeable: from 4.5.0 through 4.9.6; from 5.0.0 before 5.0.2 — fixed in 5.0.2
How to fix
Upgrade to a fixed version: openzeppelin-contracts 4.9.6, 5.0.2; OpenZeppelin Contracts Upgradeable 5.0.2. Check the vendor advisory for mitigations.
References
- https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/commit/2d081f24cac1a867f6f73d512f2022e1fa987854
- https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/commit/723f8cab09cdae1aca9ec9cc1cfa040c2d4b06c1
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/92224533b1263772b0774eec3134e132a3d7b2a6
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/a6286d0fded8771b3a645e5813e51993c490399c
- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-9vx6-7xxf-x967
- https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/commit/2d081f24cac1a867f6f73d512f2022e1fa987854
- https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/commit/723f8cab09cdae1aca9ec9cc1cfa040c2d4b06c1
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/92224533b1263772b0774eec3134e132a3d7b2a6
- https://github.com/OpenZeppelin/openzeppelin-contracts/commit/a6286d0fded8771b3a645e5813e51993c490399c
- https://github.com/OpenZeppelin/openzeppelin-contracts/security/advisories/GHSA-9vx6-7xxf-x967
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