CVE-2021-41556
published 2022-07-28CVE-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…
PriorityP260critical10CVSS 3.1
AVNACLPRNUINSCCHIHAH
EPSS
2.13%
79.7th percentile
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
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | squirrel3 | — | — |
| fedoraproject | fedora | — | — |
| fedoraproject | fedora | — | — |
| squirrel-lang | squirrel | <= 2.2.5 | — |
| squirrel-lang | squirrel | 3.0 – 3.1 | — |
Detection & IOCsextracted from sources · hover to see the quote
- →Vulnerability resides in sqclass.cpp within the Squirrel interpreter core; monitor for exploitation attempts targeting environments embedding Squirrel Engine (e.g., game engines, cloud customization platforms) ↗
- →Attacker vector is delivery of a malicious SquirrelScript executed by a victim; flag untrusted or externally-sourced .nut/.squirrel script execution in sandboxed environments ↗
- →Abuse scenarios include cloud services with SquirrelScript customization and video games embedding a Squirrel Engine — prioritize detection in those deployment contexts ↗
- ·Affected versions are Squirrel 2.x through 2.2.5 and 3.x through 3.1; Debian stable (bullseye), testing (trixie/forky), and sid all remain open/unpatched as of tracker data ↗
- ·Sandbox escape is possible even when dangerous functionality (e.g., File System functions) is explicitly disabled — do not rely solely on feature-restriction as a mitigation ↗
CVSS provenance
nvdv3.110.0CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
osv10.0CRITICAL
vendor_debian10.0CRITICAL
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VulDB
Squirrel up to 2.2.5/3.1 Core Interpreter sqclass.cpp out-of-bounds
vuldb·2026-06-01·CVSS 10.0
CVE-2021-41556 [CRITICAL] Squirrel up to 2.2.5/3.1 Core Interpreter sqclass.cpp out-of-bounds
A vulnerability has been found in Squirrel up to 2.2.5/3.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file sqclass.cpp of the component Core Interpreter. The manipulation leads to out-of-bounds read.
This vulnerability is documented as CVE-2021-41556. The attack can be initiated remotely. There is not any exploit available.
It is recommended to apply a patch to fix this issue.
GHSA
GHSA-cm28-mc8h-9h49: sqclass
ghsa_unreviewed·2022-07-29
CVE-2021-41556 [CRITICAL] CWE-125 GHSA-cm28-mc8h-9h49: sqclass
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.
OSV
CVE-2021-41556: sqclass
osv·2022-07-28·CVSS 10.0
CVE-2021-41556 [CRITICAL] CVE-2021-41556: sqclass
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.
Debian
CVE-2021-41556: squirrel3 - sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bound...
vendor_debian·2021·CVSS 10.0
CVE-2021-41556 [CRITICAL] CVE-2021-41556: squirrel3 - sqclass.cpp in Squirrel through 2.2.5 and 3.x through 3.1 allows an out-of-bound...
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.
Scope: local
bullseye: open
forky: open
sid: open
trixie: open
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
http://www.squirrel-lang.org/#downloadhttps://blog.sonarsource.com/squirrel-vm-sandbox-escape/https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98https://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/#downloadhttps://blog.sonarsource.com/squirrel-vm-sandbox-escape/https://github.com/albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98https://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/
2022-07-28
Published