CVE-2026-0878

Name: CVE-2026-0878
Creator: NVD / NIST
Published: 2026-01-13T14:16:38.367+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8/10EPSS 0.29%

Last modified Jun 17, 2026

CVE-2026-0878 is a high-severity vulnerability rated 8/10 on the CVSS scale. 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.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

8/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N

EPSS Probability

0.29%

20.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 140.7.0
Mozilla	Firefox	< 147.0
Mozilla	Thunderbird	< 140.7.0
Mozilla	Thunderbird	< 147.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2003989Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-01/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-03/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-04/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-05/Vendor Advisory

Timeline

Published: Jan 13, 2026
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-0878?

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.

How severe is CVE-2026-0878?

CVE-2026-0878 has a CVSS score of 8/10 (HIGH severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-0878?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-0878?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST