# CVE-2026-103417: Firefox for iOS credential autofill after cross-origin navigation

Source: https://junglewise.ai/threats/cve-2026-103417-firefox-for-ios-could-autofill-saved-credentials-into-a-new-page  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-103417 · Severity: medium · CVSS 5.5 · Published 2026-10-13

Firefox for iOS could autofill saved login credentials into a webpage belonging to a different origin if the user navigated away from the original page while the login UI was still displayed. This allows an attacker to trick users into submitting their credentials to a malicious site, compromising account security across multiple services.

Technologies: [Mozilla Firefox for iOS](https://junglewise.ai/threats/technologies/firefox-for-ios). Vendors: [Mozilla](https://junglewise.ai/threats/vendors/mozilla).

## Quick answers

**Is CVE-2026-103417 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103417 being exploited in the wild.

**How severe is CVE-2026-103417?** Medium severity, with a CVSS score of 5.5, published 13 October 2026.

**Which products and versions are affected?** Mozilla Firefox for iOS before 157.1.

**Is there a fix for CVE-2026-103417?** Yes: fixed in Firefox for iOS 157.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-103417 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-103417?** Check whether you run Mozilla Firefox for iOS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Firefox for iOS 157.1

## Technical details

The vulnerability occurs in Firefox for iOS's saved-login autofill mechanism, which failed to validate that the target page's origin matched the page where credentials were originally requested. If a cross-origin navigation occurred while the saved-login UI was open, autofill would proceed on the new page without origin verification. An attacker can exploit this via a page that triggers credential selection and then navigates to a malicious site, causing the victim's credentials to be filled and submitted to the attacker's domain.

## Affected products

- Mozilla Firefox for iOS before 157.1

## Timeline

- 2026-10-05: disclosed
- 2026-10-05: patched

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2068171](https://bugzilla.mozilla.org/show_bug.cgi?id=2068171)
- [https://www.mozilla.org/security/advisories/mfsa2026-105/](https://www.mozilla.org/security/advisories/mfsa2026-105/)

## Related threats

- [Mozilla Firefox for iOS privilege escalation](https://junglewise.ai/threats/cve-2026-121843-privilege-escalation-in-firefox-for-ios-this-vulnerability-was)
- [Mozilla Firefox for iOS privilege escalation in Reader View](https://junglewise.ai/threats/cve-2026-121842-privilege-escalation-in-the-reader-view-component-in-firefox-for)
- [Firefox for iOS information disclosure](https://junglewise.ai/threats/cve-2026-121841-other-issue-in-firefox-for-ios-this-vulnerability-was-fixed-in)
- [Firefox for iOS FaceTime protocol handler spoofing](https://junglewise.ai/threats/cve-2026-116632-a-malicious-web-page-could-insert-arbitrary-text-into-the)
- [Firefox for iOS external protocol handler spoofing via tel link](https://junglewise.ai/threats/cve-2026-116631-a-malicious-web-page-could-open-a-tel-link-in-a-window-that-was)