CVE-2026-0878
High
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.
SeverityHigh
CVSS8.0
Exploit probability—
Product
Mozilla Firefox
PublishedJan 13, 2026
First seenJan 13, 2026
How to fix
Update
- mozilla firefox140.7.0, 147.0 or later
- mozilla thunderbird140.7.0, 147.0 or later
Vendor advisories
- access.redhat.com/errata/RHSA-2026:2231
- access.redhat.com/errata/RHSA-2026:2271
- access.redhat.com/errata/RHSA-2026:2286
- access.redhat.com/errata/RHSA-2026:0667
- access.redhat.com/errata/RHSA-2026:2220
- access.redhat.com/errata/RHSA-2026:2074
- access.redhat.com/errata/RHSA-2026:1471
- access.redhat.com/errata/RHSA-2026:2073
- access.redhat.com/errata/RHSA-2026:1461
- access.redhat.com/errata/RHSA-2026:2070
- access.redhat.com/errata/RHSA-2026:1487
- access.redhat.com/errata/RHSA-2026:2069
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mozilla firefox | v < 140.7.0, v < 147.0 | 140.7.0, 147.0 |
| mozilla thunderbird | v < 140.7.0, v < 147.0 | 140.7.0, 147.0 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.