CVE-2026-85268

Cross-Site Scripting (XSS) in Firebase Auth Handler via Malicious Bundle ID

State: Published
Severity: 8.7 High
Published: Oct 30, 2026
Updated: Oct 30, 2026
Reserved: Sep 3, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	8.7 High	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	GoogleCloud

Weaknesses

CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')

Affected Products

Product	Versions
Identity Platform and Firebase AuthenticationGoogle Cloud	before 2026-08-14Affected

References

https://firebase.google.com/support/releases#auth-helper-fix

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