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.

CVSS v3.1

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

CVSS v3.1

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

EPSS

0.25% chance of exploitation in the next 30 days, 17th percentile

Published

2026-01-08

Proof-of-concept exploits (1)

• advisories/GHSA-m7j5-rq9j-6jj9

References

• CVE Record
• NVD entry

Related

• CVE-2026-21871
• CVE-2026-21873
• CVE-2026-2187
• CVE-2026-21874
• CVE-2026-21862
• CVE-2026-21876