zauberzeug nicegui up to 3.4.x ui.sub_pages cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.8$0-$5k0.00

Summaryinfo

A vulnerability marked as problematic has been reported in zauberzeug nicegui up to 3.4.x. This vulnerability affects the function ui.sub_pages. This manipulation causes cross site scripting. This vulnerability is tracked as CVE-2026-21873. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in zauberzeug nicegui up to 3.4.x. Affected by this vulnerability is the function ui.sub_pages. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-21873 since 01/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 3.5.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.8

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔒

CNA Base Score: 7.2
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: nicegui 3.5.0

Timelineinfo

01/05/2026 CVE reserved
01/08/2026 +3 days Advisory disclosed
01/08/2026 +0 days VulDB entry created
01/16/2026 +7 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-mhpg-c27v-6mxr
Status: Confirmed

CVE: CVE-2026-21873 (🔒)
GCVE (CVE): GCVE-0-2026-21873
GCVE (VulDB): GCVE-100-340057

Entryinfo

Created: 01/08/2026 12:00
Updated: 01/16/2026 00:44
Changes: 01/08/2026 12:00 (66), 01/16/2026 00:44 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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