How severe is CVE-2026-21872?

CVE-2026-21872 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-2026-21872 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21872?

CVE-2026-21872 affects Zauberzeug Nicegui. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21872?

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

Does CVE-2026-21872 have an EU (EUVD) identifier?

Yes. CVE-2026-21872 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1477.

When was CVE-2026-21872 published?

CVE-2026-21872 was published on 2026-01-08 and last updated on 2026-06-17.

CVE-2026-21872

CVE-2026-21872 is a medium-severity vulnerability in Zauberzeug Nicegui 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)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1477
Weakness: CWE-79
Affected product: Zauberzeug Nicegui
Published: 2026-01-08
Last modified: 2026-06-17

Description

NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the click event listener used by ui.sub_pages, combined with attacker-controlled link rendering on the page, causes XSS when the user actively clicks on the link. This issue has been patched in version 3.5.0.

Frequently asked questions

What is CVE-2026-21872?: NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the click event listener used by ui.sub_pages, combined with attacker-controlled link rendering on the page, causes XSS when the user actively clicks on the link. This issue has been patched in version 3.5.0.
How severe is CVE-2026-21872?: CVE-2026-21872 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-2026-21872 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21872?: CVE-2026-21872 affects Zauberzeug Nicegui. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21872?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21872 have an EU (EUVD) identifier?: Yes. CVE-2026-21872 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1477.
When was CVE-2026-21872 published?: CVE-2026-21872 was published on 2026-01-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*

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