How severe is CVE-2021-3377?

CVE-2021-3377 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-3377 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3377?

CVE-2021-3377 affects Ansi Up Project Ansi Up. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3377?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3377 published?

CVE-2021-3377 was published on 2021-03-05 and last updated on 2026-06-17.

CVE-2021-3377

CVE-2021-3377 is a medium-severity vulnerability in Ansi Up Project Ansi Up with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 8% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Ansi Up Project Ansi Up
Published: 2021-03-05
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-3377?: 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.
How severe is CVE-2021-3377?: CVE-2021-3377 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-3377 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3377?: CVE-2021-3377 affects Ansi Up Project Ansi Up. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3377?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3377 published?: CVE-2021-3377 was published on 2021-03-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:ansi_up_project:ansi_up:*:*:*:*:*:node.js:*:*

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