{"id":"CVE-2026-85268","title":"Cross-Site Scripting (XSS) in Firebase Auth Handler via Malicious Bundle ID","summary":"A Cross-Site Scripting (XSS) (CWE-79) vulnerability in the auth/handler in Google Cloud Identity Platform and Firebase Authentication versions prior to 2026-08-14 on iOS allows an unauthenticated remote attacker to execute arbitrary Java…","severity":"high","cvss":8.7,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/U:Amber","cvssSource":"cna","cwe":["CWE-79"],"vendor":"Google Cloud","product":"Identity Platform and Firebase Authentication","affected":["identity_platform_and_firebase_authentication < 2026-08-14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-30T16:48:10.216800Z"},"published":"2026-10-30","updated":"2026-10-30","sourceUpdated":"2026-10-30T16:48:22.519Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-85268","references":[{"url":"https://firebase.google.com/support/releases#auth-helper-fix"}],"tags":["cve.org"],"epss":0.00581,"epssPercentile":0.47851,"ingestedAt":"2026-11-05T16:24:31.089Z","slug":"CVE-2026-85268","body":"## Overview\n\nA Cross-Site Scripting (XSS) (CWE-79) vulnerability in the auth/handler in Google Cloud Identity Platform and Firebase Authentication versions prior to 2026-08-14 on iOS allows an unauthenticated remote attacker to execute arbitrary JavaScript using a malicious iOS bundle ID.\n\n## Affected\n\n- `identity_platform_and_firebase_authentication < 2026-08-14`\n\n## Remediation\n\nThis vulnerability has been patched for all users and no app updates are required. Action is only needed for developers who followed Option 4 (self-hosting the helper code) in the Firebase redirect best practices documentation https://firebase.google.com/docs/auth/web/redirect-best-practices#self-host-helper-code. These users should re-synchronize the helper code to make sure they are hosting the latest version.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}