# CVE-2026-124927: Mozilla Firefox site isolation issue in Graphics WebRender

Source: https://junglewise.ai/threats/cve-2026-124927-site-isolation-issue-in-the-graphics-webrender-component-this  
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-2026-124927 · Severity: info · Published 2026-11-10

Firefox, a web browser used by millions worldwide, contains a site isolation flaw in its graphics rendering component. This vulnerability could allow an attacker to bypass security boundaries between websites, potentially exposing one site's data to another malicious site running in the same browser.

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

## Quick answers

**Is CVE-2026-124927 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124927 being exploited in the wild.

**How severe is CVE-2026-124927?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** Mozilla Firefox before 160; Mozilla Firefox ESR before 153.7.

**Is there a fix for CVE-2026-124927?** Yes: fixed in Firefox 160, Firefox ESR 153.7. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-124927 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-124927?** Check whether you run Mozilla Firefox or Mozilla Firefox ESR 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 160, Firefox ESR 153.7

## Technical details

A site isolation issue exists in the Graphics: WebRender component of Firefox. The vulnerability allows incorrect boundary handling that could permit cross-site data access. The flaw is addressed in Firefox 160 and Firefox ESR 153.7.

## Affected products

- Mozilla Firefox before 160
- Mozilla Firefox ESR before 153.7

## Timeline

- 2026-11-10: disclosed

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2078669](https://bugzilla.mozilla.org/show_bug.cgi?id=2078669)
- [https://www.mozilla.org/security/advisories/mfsa2026-125/](https://www.mozilla.org/security/advisories/mfsa2026-125/)

## Related threats

- [Firefox ESR use-after-free in Audio/Video component](https://junglewise.ai/threats/cve-2026-124952-use-after-free-in-the-audio-video-component-this-vulnerability)
- [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)