CVE-2026-21871: PYSEC-2026-1698 - NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()

CVE-2026-21871 · Severity: low · CVSS 3.1 · Published 2026-07-07

NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()

Technologies: nicegui (PyPI). Vendors: PyPI.

Quick answers

Is CVE-2026-21871 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-21871 being exploited in the wild.
How severe is CVE-2026-21871?
Low severity, with a CVSS score of 3.1, published 7 July 2026.
Which products and versions are affected?
nicegui (PyPI) ECOSYSTEM:introduced=2.13.0,fixed=3.5.0.
Is there a fix for CVE-2026-21871?
Yes. nicegui (PyPI): upgrade to 3.5.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-21871?
Check whether you run nicegui (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • nicegui (PyPI): upgrade to 3.5.0 or later
    pip install "nicegui>=3.5.0"

Affected products

  • nicegui (PyPI) ECOSYSTEM:introduced=2.13.0,fixed=3.5.0

Identifiers

  • CVE-2026-21871
  • GHSA-7grm-h62g-5m97
  • PYSEC-2026-1698

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