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Vulnerability record · CVE-2021-3377 · published 5 March 2021

CVE-2021-3377: Ansi up project ansi up cross-site scripting vulnerability

AAnsi Up Project · Ansi Up

The npm package ansi_up converts ANSI escape codes into HTML. In ansi_up v4, ANSI escape codes can be used to create HTML hyperlinks. Due to insufficient URL sanitization, this feature is affected by a cross-site scripting (XSS) vulnerability. This issue is fixed in v5.0.0.

6.1 CVSS 3.1 Medium EPSS 8.0% · top 5.4% CWE-79 · Cross-site scripting
6.1CVSS 3.1 base score, v2 4.3
8.0%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

The npm package ansi_up converts ANSI escape codes into HTML. In ansi_up v4, ANSI escape codes can be used to create HTML hyperlinks. Due to insufficient URL sanitization, this feature is affected by a cross-site scripting (XSS) vulnerability. This issue is fixed in v5.0.0.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-3377), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.