What’s Vulnerable › Vulnerabilities
CVE-2021-41556
- Severity: critical (CVSS 10.0 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 2.8% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2022-07-28 · updated 2026-06-17
- Weakness: CWE-125
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.
Affected products
- Fedoraproject Fedora: 35, 36
- Squirrel: through 2.2.5; from 3.0 through 3.1
References
- http://www.squirrel-lang.org/#download
- https://blog.sonarsource.com/squirrel-vm-sandbox-escape/
- https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BV7SJJ44AGAX4ILIVPREIXPJ2GOG3FKV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M3FQILX7UUEERSDPMZP3MKGTMY2E7ESU/
- http://www.squirrel-lang.org/#download
- https://blog.sonarsource.com/squirrel-vm-sandbox-escape/
- https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BV7SJJ44AGAX4ILIVPREIXPJ2GOG3FKV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M3FQILX7UUEERSDPMZP3MKGTMY2E7ESU/
- https://www.sonarsource.com/blog/squirrel-vm-sandbox-escape/
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