CVE-2026-16355: JIT miscompilation in the JavaScript Engine: JIT component

Published Jul 21, 2026
·
Updated

JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 153, Firefox ESR 115.38, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

Affected Software

11 affected componentsFixes available
Mozilla Firefox<153, <115.38, <140.13
Mozilla Firefox<153
153
Mozilla Firefox ESR<115.38
115.38
Mozilla Firefox ESR<140.13
140.13
Mozilla Thunderbird<140.13
140.13
Mozilla Thunderbird<153
153
Mozilla Firefox<115.38.0
Mozilla Firefox<153.0.0
Mozilla Firefox>=128.1.0<140.13.0
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 115.38
  3. Upgrade

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

    Fixed in 140.13
  4. Upgrade

    Upgrade Firefox/Thunderbird JavaScript Engine (JIT) to a version that resolves this vulnerability.

    Fixed in 153
  5. Upgrade

    Upgrade Firefox ESR JavaScript Engine (JIT) to a version that resolves this vulnerability.

    Fixed in 115.38
  6. Upgrade

    Upgrade Firefox ESR JavaScript Engine (JIT) to a version that resolves this vulnerability.

    Fixed in 140.13
  7. Upgrade

    Upgrade Thunderbird JavaScript Engine (JIT) to a version that resolves this vulnerability.

    Fixed in 153
  8. Upgrade

    Upgrade Thunderbird 140.13 JavaScript Engine (JIT) 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-2026-16355?

CVE-2026-16355 has a critical severity rating of 9.8.

2

How do I fix CVE-2026-16355?

To fix CVE-2026-16355, update to Firefox version 153, Firefox ESR 115.38, or Firefox ESR 140.13.

3

What systems are affected by CVE-2026-16355?

CVE-2026-16355 affects Mozilla Firefox, Mozilla Firefox ESR, and Mozilla Thunderbird.

4

What type of vulnerability is CVE-2026-16355?

CVE-2026-16355 is classified as a JIT miscompilation vulnerability in the JavaScript Engine.

5

When was CVE-2026-16355 published?

CVE-2026-16355 was published on July 21, 2026.

Company

Resources

Contact

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