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CVE-2021-3163

22
FAUCET Score

CVE-2021-3163 describes a stored Cross-Site Scripting (XSS) vulnerability in the HTML editor of Slab Quill version 4.8.0. An attacker can inject malicious JavaScript by embedding a crafted onloadstart attribute within an IMG element in a text field. This medium-severity vulnerability (CVSS 6.1) requires user interaction (UI:R) and could lead to limited confidentiality and integrity impacts (C:L/I:L). There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
4.8.0CPE matchmatch criteria
cpe:2.3:a:slab:quill:4.8.0:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.31%
Probability of exploitation in next 30 days
EPSS Percentile
67.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0131 is in the 80th percentile among its peer group of 26,234 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

npmGHSA-4943-9vgg-gr5rmedium

Cross-site Scripting in quill

May 10, 2021

References

burninatorsec.blogspot.com / 2021/04/cve-2021-3163-xss-slab-quill-js.html
ExploitThird Party Advisory
github.com / quilljs/quill/issues/3273
Broken LinkIssue TrackingThird Party Advisory
github.com / quilljs/quill/issues/3364
ExploitIssue TrackingThird Party Advisory
quilljs.com
Product