# CVE-2026-118004: Firefox incorrect boundary conditions in CSS Transitions and Animations

Source: https://junglewise.ai/threats/cve-2026-118004-incorrect-boundary-conditions-in-the-css-transitions-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-118004 · Severity: info · Published 2026-10-27

Firefox, a web browser used by millions to access internet content, contains an incorrect boundary condition vulnerability in its CSS animation engine. An attacker could exploit this flaw through a malicious website to potentially crash the browser or execute arbitrary code, compromising user data and system security.

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-2026-118004 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-118004 being exploited in the wild.

**How severe is CVE-2026-118004?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Mozilla Firefox before 159; Mozilla Firefox ESR before 153.6.

**Is there a fix for CVE-2026-118004?** Yes: fixed in Firefox 159, Firefox ESR 153.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-118004 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-118004?** 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 159, Firefox ESR 153.6

## Technical details

An incorrect boundary condition exists in the CSS Transitions and Animations component of Firefox. The vulnerability can be triggered through crafted CSS animations delivered via a web page, requiring user interaction to visit the malicious site. A successful exploit could lead to memory corruption or code execution within the browser's security context.

## Affected products

- Mozilla Firefox before 159
- Mozilla Firefox ESR before 153.6

## Timeline

- 2026-10-27: disclosed

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2077756](https://bugzilla.mozilla.org/show_bug.cgi?id=2077756)
- [https://www.mozilla.org/security/advisories/mfsa2026-118/](https://www.mozilla.org/security/advisories/mfsa2026-118/)

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