# CVE-2024-27094: OpenZeppelin Contracts base64 encoding may read from potentially dirty memory

> Attackers can read potentially dirty memory beyond input buffers in Base64 encoding, exposing sensitive data in smart contracts.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Feb 2024
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-9vx6-7xxf-x967

## What is CVE-2024-27094?

CVE-2024-27094 is a medium-severity vulnerability in openzeppelin-contracts, published on 29 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2024-27094?

8 open source packages ship an affected version, including @openzeppelin/contracts and @openzeppelin/contracts-upgradeable. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@openzeppelin/contracts` | npm | From 4.5.0 | 4.9.6 |
| `@openzeppelin/contracts` | npm | From 4.5.0 | 4.9.6 |
| `@openzeppelin/contracts` | npm | From 5.0.0-rc.0 | 5.0.2 |
| `@openzeppelin/contracts` | npm | From 5.0.0-rc.0 | 5.0.2 |
| `@openzeppelin/contracts-upgradeable` | npm | From 4.5.0 | 4.9.6 |
| `@openzeppelin/contracts-upgradeable` | npm | From 4.5.0 | 4.9.6 |
| `@openzeppelin/contracts-upgradeable` | npm | From 5.0.0-rc.0 | 5.0.2 |
| `@openzeppelin/contracts-upgradeable` | npm | From 5.0.0-rc.0 | 5.0.2 |

Products: Openzeppelin Contracts, Openzeppelin Contracts Upgradeable.

## How do I fix CVE-2024-27094?

Upgrade @openzeppelin/contracts to a fixed version for your release line: 4.9.6 or 5.0.2.

## Is CVE-2024-27094 being exploited?

There is no known exploitation of CVE-2024-27094 in the wild and no public exploit code.

## Other vulnerabilities in openzeppelin-contracts

- [CVE-2021-39167](https://insights.sbomify.com/CVE-2021-39167/): TimelockController vulnerability in OpenZeppelin Contracts (critical 10.0)
- [CVE-2021-39168](https://insights.sbomify.com/CVE-2021-39168/): TimelockController vulnerability in OpenZeppelin Contracts (critical 10.0)
- [CVE-2021-41264](https://insights.sbomify.com/CVE-2021-41264/): UUPSUpgradeable vulnerability in OpenZeppelin Contracts (critical 9.8)
- [CVE-2022-35961](https://insights.sbomify.com/CVE-2022-35961/): ECDSA signature malleability in OpenZeppelin Contracts (high 7.9)
- [CVE-2022-31198](https://insights.sbomify.com/CVE-2022-31198/): GovernorVotesQuorumFraction updates to quorum may affect past defeated proposals in @openzeppelin/contracts (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-27094 and fix it if it is affected.

What it is: CVE-2024-27094 is a medium-severity vulnerability in openzeppelin-contracts, published on 29 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-27094 in the wild and no public exploit code.

Affected packages and fixed versions:
- @openzeppelin/contracts (npm): affected from 4.5.0; fixed in 4.9.6
- @openzeppelin/contracts (npm): affected from 4.5.0; fixed in 4.9.6
- @openzeppelin/contracts (npm): affected from 5.0.0-rc.0; fixed in 5.0.2
- @openzeppelin/contracts (npm): affected from 5.0.0-rc.0; fixed in 5.0.2
- @openzeppelin/contracts-upgradeable (npm): affected from 4.5.0; fixed in 4.9.6
- @openzeppelin/contracts-upgradeable (npm): affected from 4.5.0; fixed in 4.9.6
- @openzeppelin/contracts-upgradeable (npm): affected from 5.0.0-rc.0; fixed in 5.0.2
- @openzeppelin/contracts-upgradeable (npm): affected from 5.0.0-rc.0; fixed in 5.0.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-27094/ (Markdown: https://insights.sbomify.com/CVE-2024-27094/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-27094
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-27094
- OSV: https://osv.dev/vulnerability/CVE-2024-27094

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-27094/
Summaries are generated and may contain mistakes; the official description above is the record.