# CVE-2021-41556: squirrel3: sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that...

CVE-2021-41556 is fixed in squirrel3 on 1 platform by DEBIAN-CVE-2021-41556 (version 3.1-8.2+deb13u1), released July 28, 2022. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2021-41556
- Priority: Urgent
- CVSS: 10.0 (critical)
- EPSS: 0.0292
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 28, 2022

## Description

sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bounds read (in the core interpreter) that can lead to Code Execution. If a victim executes an attacker-controlled squirrel script, it is possible for the attacker to break out of the squirrel script sandbox even if all dangerous functionality such as File System functions has been disabled. An attacker might abuse this bug to target (for example) Cloud services that allow customization via SquirrelScripts, or distribute malware through video games that embed a Squirrel Engine.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | squirrel3 Debian 13.5 (trixie) | 3.1-8.2+deb13u1 | [DEBIAN-CVE-2021-41556](https://patchblox.com/security/data/fix/linux/debian-cve-2021-41556.md) | Jul 28, 2022 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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