Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-41556

32
FAUCET Score

CVE-2021-41556 is a critical out-of-bounds read vulnerability in Squirrel versions 2.2.5 and 3.x through 3.1, affecting products like Fedora and Squirrel-lang. This flaw allows an unauthenticated attacker to achieve remote code execution by tricking a victim into executing a specially crafted Squirrel script, even within sandboxed environments. With a CVSS score of 10.0 (Critical), it presents a severe risk of complete compromise (Confidentiality, Integrity, Availability) with low attack complexity. While there is no evidence of active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered some community discussion and media coverage, indicating awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.2.5CPE matchmatch criteria
cpe:2.3:a:squirrel-lang:squirrel:*:*:*:*:*:*:*:*
>= 3.0, <= 3.1CPE matchmatch criteria
cpe:2.3:a:squirrel-lang:squirrel:*:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
36CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

10.0CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.64%
Probability of exploitation in next 30 days
EPSS Percentile
84.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0264 is in the 70th percentile among its peer group of 36,833 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

sonarsource.com / blog/squirrel-vm-sandbox-escape
blog.sonarsource.com / squirrel-vm-sandbox-escape
ExploitThird Party Advisory
github.com / albertodemichelis/squirrel/commit/23a0620658714b996d20da3d4dd1a0dcf9b0bd98
PatchThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/BV7SJJ44AGAX4ILIVPREIXPJ2GOG3FKV
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/M3FQILX7UUEERSDPMZP3MKGTMY2E7ESU
squirrel-lang.org
Third Party Advisory