# CVE-2026-124943: Firefox use-after-free in Layout component

Source: https://junglewise.ai/threats/cve-2026-124943-use-after-free-in-the-layout-component-this-vulnerability-was  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-124943 · Severity: info · Published 2026-11-10

Firefox, a web browser used by millions worldwide, contains a use-after-free vulnerability in its Layout component that could allow an attacker to crash the browser or potentially execute arbitrary code. This vulnerability was fixed in Firefox version 160. Users running older versions may experience browser instability or be exploited through malicious web content.

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

## Quick answers

**Is CVE-2026-124943 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124943 being exploited in the wild.

**How severe is CVE-2026-124943?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** Mozilla Firefox.

**Is there a fix for CVE-2026-124943?** Yes: fixed in Firefox 160. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-124943 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-124943?** Check whether you run Mozilla Firefox. 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 160

## Technical details

A use-after-free flaw exists in Firefox's Layout component, which manages the rendering and positioning of web page elements. The vulnerability occurs when memory is accessed after being freed, potentially allowing an attacker to corrupt heap state or achieve code execution through crafted web content. The advisory confirms a fix is available in Firefox 160.

## Affected products

- Mozilla Firefox

## Timeline

- 2026-11-10: disclosed

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2078990](https://bugzilla.mozilla.org/show_bug.cgi?id=2078990)
- [https://www.mozilla.org/security/advisories/mfsa2026-125/](https://www.mozilla.org/security/advisories/mfsa2026-125/)

## Related threats

- [Firefox privilege escalation in Nimbus Desktop Client](https://junglewise.ai/threats/cve-2026-124951-privilege-escalation-in-the-nimbus-desktop-client-component-this)
- [Firefox same-origin policy bypass in CSS Parsing and Computation](https://junglewise.ai/threats/cve-2026-124950-same-origin-policy-bypass-in-the-css-parsing-and-computation)
- [Firefox other issue in SVG component](https://junglewise.ai/threats/cve-2026-124949-other-issue-in-the-svg-component-this-vulnerability-was-fixed-in)
- [Mozilla Firefox use-after-free in Graphics component](https://junglewise.ai/threats/cve-2026-124948-incorrect-boundary-conditions-use-after-free-in-the-graphics)
- [Firefox incorrect boundary conditions in Graphics component](https://junglewise.ai/threats/cve-2026-124947-incorrect-boundary-conditions-in-the-graphics-component-this)