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Vulnerability details: VCID-xv1m-pvjj-mfhn
Vulnerability ID VCID-xv1m-pvjj-mfhn
Aliases CVE-2026-21872
GHSA-m7j5-rq9j-6jj9
Summary NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links An unsafe implementation in the `click` event listener used by `ui.sub_pages`, combined with attacker-controlled link rendering on the page, causes an XSS when the user actively clicks on the link.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.0002 https://api.first.org/data/v1/epss?cve=CVE-2026-21872
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-m7j5-rq9j-6jj9
cvssv3.1 6.1 https://github.com/zauberzeug/nicegui
generic_textual MODERATE https://github.com/zauberzeug/nicegui
cvssv3.1 6.1 https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
generic_textual MODERATE https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
ssvc Track https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
cvssv3.1 6.1 https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
cvssv3.1_qr MODERATE https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
generic_textual MODERATE https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
ssvc Track https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
cvssv3.1 6.1 https://nvd.nist.gov/vuln/detail/CVE-2026-21872
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2026-21872
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-21872
https://github.com/zauberzeug/nicegui
https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
CVE-2026-21872 https://nvd.nist.gov/vuln/detail/CVE-2026-21872
GHSA-m7j5-rq9j-6jj9 https://github.com/advisories/GHSA-m7j5-rq9j-6jj9
GHSA-m7j5-rq9j-6jj9 https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://github.com/zauberzeug/nicegui
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-01-08T15:12:53Z/ Found at https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:P/A:N/T:P/P:M/B:A/M:M/D:T/2026-01-08T15:12:53Z/ Found at https://github.com/zauberzeug/nicegui/security/advisories/GHSA-m7j5-rq9j-6jj9
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-21872
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.06069
EPSS Score 0.0002
Published At May 30, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-05-30T21:05:47.183693+00:00 GitLab Importer Import https://gitlab.com/gitlab-org/advisories-community/-/blob/main/pypi/nicegui/CVE-2026-21872.yml 38.6.0