{"answers":{"affected":"3 open source packages ship an affected version, including nicegui. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21871 exists.","fix":"Upgrade nicegui to 3.5.0 or later.","what":"CVE-2026-21871 is a medium-severity cross-site scripting vulnerability in zauberzeug nicegui, published on 8 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-21871 and fix it if it is affected.\n\nWhat it is: CVE-2026-21871 is a medium-severity cross-site scripting vulnerability in zauberzeug nicegui, published on 8 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21871 exists.\n\nAffected packages and fixed versions:\n- nicegui (PyPI): affected from 2.13.0; fixed in 3.5.0\n- nicegui (PyPI): affected from 2.13.0; fixed in 3.5.0\n- nicegui (PyPI): affected from 2.13.0; fixed in 3.5.0\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-21871/ (Markdown: https://insights.sbomify.com/CVE-2026-21871/index.md)","id":"CVE-2026-21871","markdown":"https://insights.sbomify.com/CVE-2026-21871/index.md","name":"CVE-2026-21871","record":{"aliases":["GHSA-7grm-h62g-5m97","PYSEC-2026-1698"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"Python UI framework","requires_auth":"none","summary":"Attackers can execute arbitrary JavaScript in victims' browsers if developers pass untrusted input to specific navigation functions in NiceGUI.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"nicegui","vendor":"zauberzeug"}],"cvss":{"score":6.1,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-79","name":"Improper Neutralization of Input During Web Page Generation"}],"description":"NiceGUI is a Python-based UI framework. From versions 2.13.0 to 3.4.1, there is a XSS risk in NiceGUI when developers pass attacker-controlled strings into ui.navigate.history.push() or ui.navigate.history.replace(). These helpers are documented as History API wrappers for updating the browser URL without page reload. However, if the URL argument is embedded into generated JavaScript without proper escaping, a crafted payload can break out of the intended string context and execute arbitrary JavaScript in the victim’s browser. Applications that do not pass untrusted input into ui.navigate.history.push/replace are not affected. This issue has been patched in version 3.5.0.","ecosystems":["PyPI"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"NiceGUI is vulnerable to XSS via Unescaped URL in ui.navigate.history.push() / replace()","id":"CVE-2026-21871","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":3,"n_references":2,"next":{"headline":"NiceGUI apps are vulnerable to XSS which uses `ui.sub_pages` and render arbitrary user-provided links","id":"CVE-2026-21872"},"packages":[{"ecosystem":"PyPI","fixed":["3.5.0"],"introduced":["2.13.0"],"last_affected":[],"package":"nicegui","purl":null,"source":"GHSA-7grm-h62g-5m97"},{"ecosystem":"PyPI","fixed":["3.5.0"],"introduced":["2.13.0"],"last_affected":[],"package":"nicegui","purl":"pkg:pypi/nicegui","source":"GHSA-7grm-h62g-5m97"},{"ecosystem":"PyPI","fixed":["3.5.0"],"introduced":["2.13.0"],"last_affected":[],"package":"nicegui","purl":"pkg:pypi/nicegui","source":"PYSEC-2026-1698"}],"prev":{"headline":"The BACnet Protocol Stack library has an Off-by-one Stack-based Buffer Overflow in tokenizer_string","id":"CVE-2026-21870"},"products":["nicegui"],"published":"2026-01-08","related":[{"cvss_score":7.5,"headline":"NiceGUI's Path Traversal via Unsanitized FileUpload.name Enables Arbitrary File Write","id":"CVE-2026-25732","kev_date_added":null,"published":"2026-02-06"},{"cvss_score":7.5,"headline":"NiceGUI Path Traversal Vulnerability in app.add_media_files() Allows Arbitrary File Reading","id":"CVE-2025-66645","kev_date_added":null,"published":"2025-12-09"},{"cvss_score":7.2,"headline":"Zero-click XSS in all NiceGUI apps which uses `ui.sub_pages`","id":"CVE-2026-21873","kev_date_added":null,"published":"2026-01-08"},{"cvss_score":6.9,"headline":"NiceGUI's unvalidated chunk size parameter in media routes can cause memory exhaustion","id":"CVE-2026-33332","kev_date_added":null,"published":"2026-03-24"},{"cvss_score":6.1,"headline":"NiceGUI has XSS via Code Injection","id":"CVE-2026-27156","kev_date_added":null,"published":"2026-02-24"},{"cvss_score":6.1,"headline":"NiceGUI's XSS vulnerability in ui.markdown() allows arbitrary JavaScript execution through unsanitized HTML content","id":"CVE-2026-25516","kev_date_added":null,"published":"2026-02-06"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"PyPA Advisory Database","prefix":"PYSEC"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-01-08","vendors":["zauberzeug"]},"summary":"Attackers can execute arbitrary JavaScript in victims' browsers if developers pass untrusted input to specific navigation functions in NiceGUI.","url":"https://insights.sbomify.com/CVE-2026-21871/"}