---
title: "CVE-2026-103418: Firefox for iOS - Stored XSS"
description: "Firefox for iOS < 157.1 contains a stored XSS caused by direct interpolation of the page's HTML language attribute into translation JavaScript, letting attackers execute code in privileged content and bypass CSP, exploit requires attacker-controlled markup."
url: https://panop.io/threat-heartbeat/CVE-2026-103418/
---

# CVE-2026-103418 Firefox for iOS - Stored XSS

Firefox for iOS < 157.1 contains a stored XSS caused by direct interpolation of the page's HTML language attribute into translation JavaScript, letting attackers execute code in privileged content and bypass CSP, exploit requires attacker-controlled markup.

CVSS base score 8.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.30% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-103418)

## Details

Type

Stored XSS

Impact

Client Script Exec

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Published

13 October 2026

Updated

15 October 2026

Weakness

[CWE-79](https://cwe.mitre.org/data/definitions/79.html)

## Vendor fix

Update to Firefox for iOS 157.1 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-103418](https://nvd.nist.gov/vuln/detail/CVE-2026-103418)
- [https://bugzilla.mozilla.org/show\_bug.cgi?id=2062109](https://bugzilla.mozilla.org/show_bug.cgi?id=2062109)
- [https://www.mozilla.org/security/advisories/mfsa2026-105/](https://www.mozilla.org/security/advisories/mfsa2026-105/)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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