# CVE-2026-116631: Firefox for iOS external protocol handler spoofing via tel link

Source: https://junglewise.ai/threats/cve-2026-116631-a-malicious-web-page-could-open-a-tel-link-in-a-window-that-was  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-26. Updated: 2026-10-26  
License: CC BY 4.0 with a link back

CVE-2026-116631 · Severity: medium · CVSS 5.4 · Published 2026-10-26

Firefox for iOS allows a malicious website to open a phone-call prompt that appears to originate from a different legitimate website, tricking users into calling attacker-controlled numbers. An attacker could exploit this to conduct social engineering attacks or financial fraud by spoofing trusted organizations in the phone-call UI.

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-2026-116631 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116631 being exploited in the wild.

**How severe is CVE-2026-116631?** Medium severity, with a CVSS score of 5.4, published 26 October 2026.

**Which products and versions are affected?** Mozilla Firefox for iOS before 156.1.

**Is there a fix for CVE-2026-116631?** Yes: fixed in Firefox for iOS 156.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-116631 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-116631?** 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 156.1

## Technical details

A malicious website can open a tel: protocol link in a browser window showing a different website, causing the resulting phone-call prompt to appear as though the legitimate site requested the call. This is a UI spoofing vulnerability affecting the external protocol handler in Firefox for iOS. The vulnerability allows network-based attackers without special privileges to trick users into calling numbers controlled by the attacker.

## Affected products

- Mozilla Firefox for iOS before 156.1

## Timeline

- 2026-10-26: disclosed
- 2026-10-26: patched

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=1297353](https://bugzilla.mozilla.org/show_bug.cgi?id=1297353)
- [https://www.mozilla.org/security/advisories/mfsa2026-117/](https://www.mozilla.org/security/advisories/mfsa2026-117/)

## Related threats

- [Mozilla Firefox for iOS privilege escalation](https://junglewise.ai/threats/cve-2026-121843-privilege-escalation-in-firefox-for-ios-this-vulnerability-was)
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- [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 XSS via HTML language attribute in Translation Services](https://junglewise.ai/threats/cve-2026-103418-firefox-for-ios-directly-interpolated-the-page-s-html-language)