CVE-2026-16363: JIT miscompilation in the JavaScript: WebAssembly component

Published Jul 21, 2026
·
Updated

JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Affected Software

9 affected componentsFixes available
Mozilla Firefox=153, =140.13
Mozilla Firefox<153
153
Mozilla Firefox ESR<140.13
140.13
Mozilla Thunderbird<140.13
140.13
Mozilla Thunderbird<153
153
Mozilla Firefox<140.13.0
Mozilla Firefox<153.0.0
Mozilla Thunderbird<140.13.0
Mozilla Thunderbird>=141.0<153.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 153
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 140.13
  3. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 153
  4. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.13
  5. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 153
  6. Upgrade

    Upgrade Thunderbird ESR to a version that resolves this vulnerability.

    Fixed in 140.13

Event History

Jul 21, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·12:37 PM
Data Sourced
via MITRE·12:37 PM
Description
Data Sourced
via NVD·01:17 PM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is the severity of CVE-2026-16363?

The severity of CVE-2026-16363 is rated as critical with a score of 9.8.

2

How do I fix CVE-2026-16363?

To fix CVE-2026-16363, update to Firefox version 153, Firefox ESR version 140.13, Thunderbird version 153, or Thunderbird ESR version 140.13.

3

What type of vulnerability is CVE-2026-16363?

CVE-2026-16363 is a Just-In-Time (JIT) miscompilation vulnerability in the WebAssembly component of JavaScript.

4

Which software is affected by CVE-2026-16363?

CVE-2026-16363 affects Mozilla Firefox, Mozilla Thunderbird, and Mozilla Firefox ESR.

5

When was CVE-2026-16363 published?

CVE-2026-16363 was published on July 21, 2026.

Company

Resources

Contact

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