# CVE-2023-46232: era-compiler-vyper First Immutable Variable Initialization vulnerability

> A compiler bug causes incorrect initialization of immutable variables in Vyper contracts, leading to data corruption that requires upgrading and redeploying contracts.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Oct 2023
- **Updated:** 10 Sep 2024
- **Also known as:** GHSA-h8jv-969m-94r4

## What is CVE-2023-46232?

CVE-2023-46232 is a medium-severity vulnerability in matter-labs era-compiler-vyper, published on 25 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

era-compiler-vyper is the EraVM Vyper compiler for zkSync Era, a layer 2 rollup that uses zero-knowledge proofs to scale Ethereum. Prior to era-compiler-vype version 1.3.10, a bug prevented the initialization of the first immutable variable for Vyper contracts meeting certain criteria. The problem arises when there is a String or Array with more 256-bit words allocated than initialized. It results in the second word’s index unset, that is effectively set to 0, so the first immutable value with the actual 0 index is overwritten in the ImmutableSimulator. Version 1.3.10 fixes this issue by setting all indexes in advance. The problem will go away, but it will get more expensive if the user allocates a lot of uninitialized space, e.g. `String[4096]`. Upgrading and redeploying affected contracts is the only way of working around the issue.

Weakness: CWE-471 (Modification of Assumed-Immutable Data (MAID))

## Which versions are affected by CVE-2023-46232?

It affects 1 product.


Products: Matter-Labs Zkvyper.

## How do I fix CVE-2023-46232?

No fix has been published for CVE-2023-46232 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-46232 being exploited?

There is no known exploitation of CVE-2023-46232 in the wild and no public exploit code.

## Other vulnerabilities in matter-labs era-compiler-vyper

- [CVE-2024-43366](https://insights.sbomify.com/CVE-2024-43366/): zkvyper ignored loop range bounds (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-46232 and fix it if it is affected.

What it is: CVE-2023-46232 is a medium-severity vulnerability in matter-labs era-compiler-vyper, published on 25 Oct 2023. 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-2023-46232 in the wild and no public exploit code.

Affected product: matter-labs era-compiler-vyper. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2023-46232/ (Markdown: https://insights.sbomify.com/CVE-2023-46232/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-46232
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-46232
- OSV: https://osv.dev/vulnerability/CVE-2023-46232

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-46232/
Summaries are generated and may contain mistakes; the official description above is the record.