XSS in Zauberzeug Nicegui
CVE-2026-27156
NiceGUI is a Python-based UI framework. Prior to version 3.8.0, several NiceGUI APIs that execute methods on client-side elements (`Element.run_method()`, `AgGrid.run_grid_method()`, `EChart.run_chart_method()`, and others) use an `eval()` fallback in the JavaScript-side `runMethod()` function. When user-controlled input is passed as the method name, an attacker can inject arbitrary JavaScript that executes in the victim's browser. Additionally, `Element.run_method()` and `Element.get_computed_prop()` used string interpolation instead of `json.dumps()` for the method/property name, allowing quote injection to break out of the intended string context. Version 3.8.0 contains a fix.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (17.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Zauberzeug Nicegui — versions < 3.8.0
Weakness classification (CWE)
References
- github.com/zauberzeug/nicegui/security/advisories/GHSA-78qv-3mpx-9cqq (Mitigation, Vendor Advisory)
- github.com/zauberzeug/nicegui/commit/1861f59cc374ca0dc9d970b157ef3774720f8dbf (Patch)
Frequently asked questions
- What is CVE-2026-27156?
- CVE-2026-27156 is a medium-severity vulnerability in Zauberzeug Nicegui, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-02-24.
- How severe is CVE-2026-27156?
- Medium severity. CVSS v3 base score is 6.1 out of 10.