---
id: GHSA-mc9m-6fm9-pghc
title: 'Zoo Design Studio: Memory-corruption in memory handling of lib-kcl'
summary: 'Zoo Design Studio: Memory-corruption in memory handling of lib-kcl'
severity: medium
cwe:
  - CWE-362
  - CWE-416
vendor: zoo-kcl
product: zoo-kcl
ecosystem: pip
affected:
  - zoo-kcl < 0.3.153
  - kcl-lib < 0.2.153
patched:
  - zoo-kcl 0.3.153
  - kcl-lib 0.2.153
published: '2026-08-20'
updated: '2026-08-20'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-mc9m-6fm9-pghc'
references:
  - url: >-
      https://github.com/KittyCAD/modeling-app/security/advisories/GHSA-mc9m-6fm9-pghc
  - url: 'https://github.com/advisories/GHSA-mc9m-6fm9-pghc'
tags:
  - ghsa
  - pip
ingestedAt: '2026-08-20T18:59:55.331Z'
---

## Overview

A race condition in kcl-lib can result in a use-after-free when accessing environments concurrently. During Vec reallocation, the previous buffer containing Box pointers is freed and replaced. A concurrent get_env operation that has already loaded a pointer to the old buffer may subsequently index into freed memory and retrieve a stale or corrupted Pin<Box<Environment>>.

## Affected packages

- `zoo-kcl < 0.3.153`
- `kcl-lib < 0.2.153`

## Remediation

Upgrade to a patched release:

- `zoo-kcl 0.3.153`
- `kcl-lib 0.2.153`