---
id: "CVE-2026-85268"
kind: "vulnerability"
aliases: ["CVE-2026-85268"]
title: "Firebase Authentication: XSS via malicious iOS bundle ID runs JavaScript"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "vendor"
products: []
ecosystems: []
tags: ["firebase", "google-cloud", "identity-platform", "ios", "vendor"]
not_affected_if: ["no-firebase-auth", "no-ios-auth-flow"]
published_at: "2026-10-30T11:17:33+00:00"
first_seen_at: "2026-10-30T11:29:51+00:00"
updated_at: "2026-10-30T11:31:22+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-85268", "first_seen_at": "2026-10-30T11:29:51+00:00"}]
---

# Firebase Authentication: XSS via malicious iOS bundle ID runs JavaScript

Google Cloud Identity Platform and Firebase Authentication's auth handler on iOS does not safely handle a malicious iOS bundle ID, so an attacker can inject and run arbitrary JavaScript in a victim's browser. The flaw is reachable without an account, per the NVD description.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether the app uses Firebase Authentication or Google Cloud Identity Platform with the auth handler on iOS.

## Fix

- Firebase Authentication and Google Cloud Identity Platform: versions prior to 2026-08-14 are affected; move to a release at or after that date.
- Exact fixed version: unknown

## Timeline

- 2026-10-30T11:29:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-85268

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_