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TI-2026-20625 Aliases CVE-2026-25516GHSA-v82v-c5x8-w282

NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution through unsanitized HTML content

Priority LOW 27CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Cross-site scripting
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.

Summary

NiceGUI is a Python-based UI framework. The ui.markdown() component uses the markdown2 library to convert markdown content to HTML, which is then rendered via innerHTML. By default, markdown2 allows raw HTML to pass through unchanged. This means that if an application renders user-controlled content through ui.markdown(), an attacker can inject malicious HTML containing JavaScript event handlers. Unlike other NiceGUI components that render HTML (ui.html(), ui.chat_message(), ui.interactive_image()), the ui.markdown() component does not provide or require a sanitize parameter, leaving applications vulnerable to XSS attacks. This vulnerability is fixed in 3.7.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00276 20th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed nicegui (zauberzeug): 3.7.0nicegui (PyPI): 3.7.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
zauberzeugniceguibefore 3.7.03.7.0Patch availableCNA
—nicegui (PyPI)before 3.7.03.7.0Patch availableGHSA-v82v-c5x8-w282
  • nicegui Vendorzauberzeug Affected before 3.7.0 Fixed in 3.7.0 Patch available CNA
  • nicegui (PyPI) Vendor— Affected before 3.7.0 Fixed in 3.7.0 Patch available GHSA-v82v-c5x8-w282

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:*before 3.7.0Vulnerablezauberzeug
  • cpe:2.3:a:zauberzeug:nicegui:*:*:*:*:*:*:*:* Versions before 3.7.0 Vulnerable ·zauberzeug

Remediation

  • Fix · CNA nicegui (zauberzeug) Fixed in 3.7.0
  • Fix · GHSA-v82v-c5x8-w282 nicegui (PyPI) Fixed in 3.7.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-25516
  2. 2026-10-03 Alias added: GHSA-v82v-c5x8-w282

References

Exploit 1

Patch 1

Advisory 1

Other 1

  • TI-2025-41029 NiceGUI Path Traversal Vulnerability in app.add_media_files() Allows Arbitrary File Reading CVSS 3.1HIGH 7.5
  • TI-2026-17574 Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages` CVSS 3.1HIGH 7.2
  • TI-2026-17575 NiceGUI has Redis connection leak via tab storage causes service degradation CVSS 3.1MEDIUM 5.3
  • TI-2026-17573 NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links CVSS 3.1MEDIUM 6.1
  • TI-2026-17572 NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace() CVSS 3.1MEDIUM 6.1
  • TI-2025-40897 NiceGUI Stored/Reflected XSS in ui.interactive_image via unsanitized SVG content CVSS 3.1MEDIUM 6.1
See all 11 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences