CVE-2026-0878: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component

Published Jan 13, 2026
·
Updated

Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147 and Firefox ESR < 140.7.

Other sources

Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

— MITRE

Affected Software

8 affected componentsFixes available
Mozilla Firefox<147
147
Mozilla Firefox ESR<140.7
140.7
Mozilla Thunderbird<140.7
140.7
Mozilla Thunderbird<147
147
Mozilla Firefox<140.7.0
Mozilla Firefox<147.0
Mozilla Thunderbird<140.7.0
Mozilla Thunderbird<147.0

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 147
  2. Upgrade

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

    Fixed in 140.7
  3. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 147
  4. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.7
  5. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 147
  6. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.7

Event History

Jan 13, 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·01:30 PM
Data Sourced
via MITRE·01:30 PM
Description
Data Sourced
via Red Hat·02:01 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 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-2026-0878?

CVE-2026-0878 is a critical vulnerability that allows for a sandbox escape in affected versions of Firefox and Firefox ESR.

2

How do I fix CVE-2026-0878?

To mitigate CVE-2026-0878, users should update to Firefox version 147 or Firefox ESR version 140.7 or later.

3

Which versions of Firefox are affected by CVE-2026-0878?

CVE-2026-0878 affects Firefox versions prior to 147 and Firefox ESR versions prior to 140.7.

4

What components are involved in CVE-2026-0878?

CVE-2026-0878 is related to a vulnerability in the Graphics: CanvasWebGL component.

5

Is CVE-2026-0878 an exploit that can be actively targeted?

Yes, CVE-2026-0878 is an exploit that can be actively targeted due to its nature as a sandbox escape vulnerability.

Company

Resources

Contact

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