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CVE-2021-3377

34
FAUCET Score

CVE-2021-3377 is a Cross-Site Scripting (XSS) vulnerability affecting versions of the npm package ansi_up prior to v5.0.0. This flaw allows attackers to inject malicious scripts into web pages by crafting ANSI escape codes that create unsanitized HTML hyperlinks. Rated as MEDIUM severity (CVSS 6.1), it requires user interaction and can lead to information disclosure or defacement. While no active exploitation or Metasploit modules are reported, Nuclei templates exist, and the vulnerability has received minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.0.0CPE matchmatch criteria
cpe:2.3:a:ansi_up_project:ansi_up:*:*:*:*:*: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
8.00%
Probability of exploitation in next 30 days
EPSS Percentile
94.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
Nuclei: CVE-2021-3377 · Jul 26, 2021
This CVE's current EPSS score of 0.0800 is in the 98th percentile among its peer group of 26,219 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 (3)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: ansi_upFixed in: 5.0.0
redhatno patchvia redhat_api
Product: Red Hat Advanced Cluster Management for Kubernetes 2Fixed in: kui-web-terminal

Vendor Advisories (2)

npmGHSA-2v5f-23xc-v9qrmedium

ansi_up cross-site scripting vulnerability

Mar 11, 2021
redhatCVE-2021-3377Moderate

nodejs-ansi_up: XSS due to insufficient URL sanitization

Jan 29, 2021

References

security.netapp.com / advisory/ntap-20241108-0002
doyensec.com / resources/Doyensec_Advisory_ansi_up4_XSS.pdf
ExploitThird Party Advisory
github.com / drudru/ansi_up/commit/c8c726ed1db979bae4f257b7fa41775155ba2e27
PatchThird Party Advisory