# CVE-2026-84135: Mozilla Firefox Focus for Android other issue

Source: https://junglewise.ai/threats/cve-2026-84135-mozilla-firefox-focus-for-android-other-issue  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-01. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-84135 · Severity: critical · CVSS 9.8 · Published 2026-09-01

Firefox Focus for Android is a lightweight privacy-focused browser for mobile devices. A security issue was discovered in the application that could have been exploited by attackers under specific conditions. The vulnerability has been patched in Firefox 155 and users should update immediately to protect their devices and data.

Technologies: [Mozilla Firefox Focus for Android](https://junglewise.ai/threats/technologies/firefox-focus-for-android), [Mozilla Firefox Mobile](https://junglewise.ai/threats/technologies/firefox-mobile). Vendors: [Mozilla](https://junglewise.ai/threats/vendors/mozilla).

## Quick answers

**Is CVE-2026-84135 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84135 being exploited in the wild.

**How severe is CVE-2026-84135?** Critical severity, with a CVSS score of 9.8, published 1 September 2026.

**Which products and versions are affected?** Mozilla Firefox Focus for Android.

**Is there a fix for CVE-2026-84135?** A patch was published on 2026-09-01: Fixed in Firefox 155 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84135 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-84135?** Check whether you run Mozilla Firefox Focus for Android or Mozilla Firefox Mobile. 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.

## Technical details

CVE-2026-84135 is an "other issue" (unspecified vulnerability class) affecting Firefox Focus for Android. The full technical details are not available in the advisory—the underlying bug (2046661) is access-restricted on Mozilla's Bugzilla. The vulnerability was fixed in Firefox 155, released on September 1, 2026. No evidence of active exploitation in the wild has been reported. Users running Firefox Focus for Android should upgrade to the patched version.

## Affected products

- Mozilla Firefox Focus for Android

## Timeline

- 2026-09-01: disclosed
- 2026-09-01: patched: Fixed in Firefox 155

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2046661](https://bugzilla.mozilla.org/show_bug.cgi?id=2046661)
- [https://www.mozilla.org/security/advisories/mfsa2026-82/](https://www.mozilla.org/security/advisories/mfsa2026-82/)

## Related threats

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- [Mozilla Firefox privilege escalation in Android](https://junglewise.ai/threats/cve-2026-84117-mozilla-firefox-privilege-escalation-in-android)
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- [Mozilla Firefox for Android clickjacking in Downloads component](https://junglewise.ai/threats/cve-2026-74980-mozilla-firefox-for-android-clickjacking-in-downloads-component)
- [Mozilla Firefox for Android spoofing in Downloads component](https://junglewise.ai/threats/cve-2026-74975-mozilla-firefox-for-android-spoofing-in-downloads-component)