{"id":"CVE-2026-85268","state":"PUBLISHED","title":"Cross-Site Scripting (XSS) in Firebase Auth Handler via Malicious Bundle ID","description":"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 JavaScript using a malicious iOS bundle ID.","publishedAt":"2026-10-30T10:20:06.249Z","updatedAt":"2026-10-30T16:48:22.519Z","severity":{"score":8.7,"label":"High","version":"4.0","vector":"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","source":"GoogleCloud"},"assigner":"GoogleCloud","products":["Google Cloud Identity Platform and Firebase Authentication"],"affected":[{"vendor":"Google Cloud","product":"Identity Platform and Firebase Authentication","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2026-08-14","versionType":"date"}],"platforms":["iOS"]}],"references":["https://firebase.google.com/support/releases#auth-helper-fix"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-30T16:54:06.455Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/85xxx/CVE-2026-85268.json","commit":"48122c4b3bcd05d954afe8acd0951f0fe166e5af","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-85268","state":"PUBLISHED","datePublished":"2026-10-30T10:20:06.249Z","dateUpdated":"2026-10-30T16:48:22.519Z","assignerShortName":"GoogleCloud","assignerOrgId":"f45cbf4e-4146-4068-b7e1-655ffc2c548c","dateReserved":"2026-09-03T16:36:41.159Z"},"containers":{"cna":{"title":"Cross-Site Scripting (XSS) in Firebase Auth Handler via Malicious Bundle ID","descriptions":[{"lang":"en","value":"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 JavaScript using a malicious iOS bundle ID."}],"affected":[{"vendor":"Google Cloud","product":"Identity Platform and Firebase Authentication","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2026-08-14","versionType":"date"}],"platforms":["iOS"]}],"references":[{"url":"https://firebase.google.com/support/releases#auth-helper-fix"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"LOW","vulnIntegrityImpact":"HIGH","subIntegrityImpact":"LOW","vulnAvailabilityImpact":"HIGH","subAvailabilityImpact":"LOW","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"AMBER","version":"4.0","baseSeverity":"HIGH","baseScore":8.7,"vectorString":"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"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GoogleCloud","orgId":"f45cbf4e-4146-4068-b7e1-655ffc2c548c","dateUpdated":"2026-10-30T10:20:06.249Z"},"impacts":[{"capecId":"CAPEC-63","descriptions":[{"lang":"en","value":"CAPEC-63 Cross-Site Scripting (XSS)"}]}],"solutions":[{"lang":"en","value":"This 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.","supportingMedia":[{"type":"text/html","base64":false,"value":"This 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 <a href=\"https://firebase.google.com/docs/auth/web/redirect-best-practices#self-host-helper-code\">Firebase redirect best practices documentation</a>. These users should re-synchronize the helper code to make sure they are hosting the latest version."}]}],"credits":[{"lang":"en","value":"Mathias Karlsson","type":"reporter"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.2"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-30T16:48:10.216800Z","id":"CVE-2026-85268","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-30T16:48:22.519Z"}}]}}}