Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-21873— Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages`

Quick assessment

Affected
zauberzeug nicegui
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NiceGUI是NiceGUI开源的一个易于使用、基于 Python 的 UI 框架。 NiceGUI 2.22.0版本至3.4.1版本存在跨站脚本漏洞，该漏洞源于pushstate事件监听器实现不安全，可能导致URL片段标识符被操纵。

CVSS 7.2 · High EPSS 0.26% · P16
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-21873

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages`
Source: CVE Program / CVE List V5
Vulnerability Description
NiceGUI is a Python-based UI framework. From versions 2.22.0 to 3.4.1, an unsafe implementation in the pushstate event listener used by ui.sub_pages allows an attacker to manipulate the fragment identifier of the URL, which they can do despite being cross-site, using an iframe. This issue has been patched in version 3.5.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
NiceGUI 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
NiceGUI是NiceGUI开源的一个易于使用、基于 Python 的 UI 框架。 NiceGUI 2.22.0版本至3.4.1版本存在跨站脚本漏洞，该漏洞源于pushstate事件监听器实现不安全，可能导致URL片段标识符被操纵。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
zauberzeug nicegui >= 2.22.0, < 3.5.0 -

II. Public POCs for CVE-2026-21873

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 7166 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-21873

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-21873 (1)

Other References for CVE-2026-21873 (1)

Same Patch Batch · zauberzeug · 2026-01-08 · 4 CVEs total

CVE-2026-21871 6.1 MEDIUM NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()
CVE-2026-21872 6.1 MEDIUM NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-pro
CVE-2026-21874 5.3 MEDIUM NiceGUI has Redis connection leak via tab storage causes service degradation

IV. Related Vulnerabilities

Same product: nicegui
Same vendor: zauberzeug
Same weakness: CWE-79

V. Comments for CVE-2026-21873

No comments yet

Leave a comment