CVE-2021-41556

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.

CVSS v3.1 NVD

10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

2.84% chance of exploitation in the next 30 days, 86th percentile

Published

2022-07-28

Updated

2026-05-29

Proof-of-concept exploits (1)

• https://blog.sonarsource.com/squirrel-vm-sandbox-escape/

Security advisories

• http://www.squirrel-lang.org/#download
• https://blog.sonarsource.com/squirrel-vm-sandbox-escape
• albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98

References

• CVE Record
• NVD entry