{"id":"CVE-2026-21873","aliases":["GHSA-mhpg-c27v-6mxr","PYSEC-2026-1702"],"url":"https://o3.security/vulnerability/CVE-2026-21873","summary":"Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages`","details":"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.","published":"2026-01-08T09:50:23.361Z","modified":"2026-08-12T03:51:35.548330125Z","cvss":{"score":7.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"nicegui","fixedVersion":"3.5.0"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/zauberzeug/nicegui/releases/tag/v3.5.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21873.json"},{"type":"ADVISORY","url":"https://github.com/zauberzeug/nicegui/security/advisories/GHSA-mhpg-c27v-6mxr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21873"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:35.548330125Z"}}