Cyber Resilience

CVE-2021-41556

CriticalPublic PoCUpdated

Published: 28 July 2022

Published
28 July 2022
Modified
29 May 2026
KEV Added
Patch
CVSS Score v3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0270 86.2th percentile
Risk Priority 22 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-41556 is a critical-severity Out-of-bounds Read (CWE-125) vulnerability in Squirrel-Lang Squirrel. Its CVSS base score is 10.0 (Critical).

Operationally, ranked in the top 13.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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…

more

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.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

squirrel-lang
squirrel
≤ 2.2.5 · 3.0 — 3.1
fedoraproject
fedora
35, 36

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References