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CVE-2021-4296

18
FAUCET Score

CVE-2021-4296 is a cross-site scripting (XSS) vulnerability found in w3c Unicorn, specifically within the ValidatorNuMessage function. This medium-severity flaw (CVSS 6.1) can be exploited remotely without authentication, requiring user interaction, and could lead to limited confidentiality and integrity impacts. While a patch is available, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 2021-06-03CPE matchmatch criteria
cpe:2.3:a:w3:unicorn:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

3.5LOW

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.1
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.52%
Probability of exploitation in next 30 days
EPSS Percentile
40.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0052 is in the 43rd percentile among its peer group of 26,220 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

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / w3c/Unicorn/commit/51f75c31f7fc33859a9a571311c67ae4e95d9c68
PatchThird Party Advisory
github.com / w3c/Unicorn/pull/212
Third Party Advisory
vuldb.com
Third Party Advisory
vuldb.com
Third Party Advisory