CVE-2021-3377: Ansi Up Project Ansi Up

Medium severity, CVSS 6.1. EPSS: 8% chance of exploitation in the next 30 days.

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.

Affected products

• Ansi Up Project Ansi Up: before 5.0.0 (fixed in 5.0.0)

Published 2021-03-05. Last modified 2026-06-17.