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CVE-2021-23543

31
FAUCET Score

CVE-2021-23543 describes a critical Sandbox Bypass vulnerability, rated 9.8 CVSS, affecting all versions of the 'realms-shim' package. This flaw stems from a Prototype Pollution attack vector, allowing remote, unauthenticated attackers to achieve high impact on confidentiality, integrity, and availability. Despite its severity, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:a:agoric:realms-shim:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.76%
Probability of exploitation in next 30 days
EPSS Percentile
75.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0176 is in the 64th percentile among its peer group of 36,897 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

No media coverage found for this CVE.

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

Remediation

Vendor Advisories (1)

npmGHSA-q4j7-v27r-fgcxcritical

Prototype Pollution in realms-shim

Jan 13, 2022

References

snyk.io / vuln/SNYK-JS-REALMSSHIM-2309908
ExploitThird Party Advisory
npmjs.com / package/realms-shim
ProductThird Party Advisory