# CVE-2026-121842: Mozilla Firefox for iOS privilege escalation in Reader View

Source: https://junglewise.ai/threats/cve-2026-121842-privilege-escalation-in-the-reader-view-component-in-firefox-for  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-09  
License: CC BY 4.0 with a link back

CVE-2026-121842 · Severity: info · Published 2026-11-09

Firefox for iOS is a mobile web browser that allows users to browse the internet and read articles. A privilege escalation vulnerability in the Reader View component could allow an attacker to gain elevated permissions within the application, potentially exposing user data or enabling further attacks. This vulnerability was fixed in Firefox for iOS version 160.0.

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-2026-121842 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121842 being exploited in the wild.

**How severe is CVE-2026-121842?** Informational severity, published 9 November 2026.

**Which products and versions are affected?** Mozilla Firefox for iOS prior to 160.0.

**Is there a fix for CVE-2026-121842?** Yes: fixed in Firefox for iOS 160.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-121842 attacked?** It is in a web application.

**Am I affected by CVE-2026-121842?** 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 160.0

## Technical details

A privilege escalation vulnerability exists in the Reader View component of Firefox for iOS. The specific attack vector and preconditions are not detailed in the advisory, but the vulnerability allows an attacker to escalate privileges. The issue has been resolved in Firefox for iOS 160.0.

## Affected products

- Mozilla Firefox for iOS prior to 160.0

## Timeline

- 2026-11-09: disclosed
- 2026-11-09: patched: Firefox for iOS 160.0 released

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2076233](https://bugzilla.mozilla.org/show_bug.cgi?id=2076233)
- [https://www.mozilla.org/security/advisories/mfsa2026-124/](https://www.mozilla.org/security/advisories/mfsa2026-124/)

## 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 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)