CVE-2026-0878
published 2026-01-13CVE-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…
PriorityP339high8CVSS 3.1
AVNACHPRNUIRSCCHIHAN
EPSS
0.42%
33.8th percentile
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.
Affected
12 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| debian | firefox-esr | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| debian | thunderbird | < firefox 147.0-1 (sid) | firefox 147.0-1 (sid) |
| mozilla | firefox | < 140.7.0 | 140.7.0 |
| mozilla | firefox | < 147.0 | 147.0 |
| mozilla | firefox | — | — |
| mozilla | thunderbird | < 140.7.0 | 140.7.0 |
| mozilla | thunderbird | < 147.0 | 147.0 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb11u1 | 1:140.7.0esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb12u1 | 1:140.7.0esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1~deb13u1 | 1:140.7.0esr-1~deb13u1 |
| mozilla | thunderbird | >= 0 < 1:140.7.0esr-1 | 1:140.7.0esr-1 |
CVSS provenance
nvdv3.18.0HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
osv8.0HIGH
vendor_debian8.0HIGH
vendor_redhat8.0HIGH
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OSV
CVE-2026-0878: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
osv·2026-01-13·CVSS 8.0
CVE-2026-0878 [HIGH] CVE-2026-0878: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
GHSA
GHSA-qc2q-rhvg-9278: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
ghsa_unreviewed·2026-01-13
CVE-2026-0878 [HIGH] CWE-20 GHSA-qc2q-rhvg-9278: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147 and Firefox ESR < 140.7.
Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2026-02-02
CVE-2025-8031 Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, bypass security restrictions, cross-site
tracing, or execute arbitrary code.
Instructions: In general, a standard system update will make all the necessary changes.
Red Hat
firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
vendor_redhat·2026-01-13·CVSS 8.0
CVE-2026-0878 [HIGH] firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue:
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Affected
Package: rhel10/thunderbird-flatpak (Red Hat Enterprise Linux 10) - Affec
Debian
CVE-2026-0878: firefox - Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL...
vendor_debian·2026·CVSS 8.0
CVE-2026-0878 [HIGH] CVE-2026-0878: firefox - Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL...
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
Scope: local
sid: resolved (fixed in 147.0-1)
Mozilla
Mozilla Foundation Security Advisory 2026-04: CVE-2026-0878
vendor_mozilla·CVSS 8.0
CVE-2026-0878 [HIGH] Mozilla Foundation Security Advisory 2026-04: CVE-2026-0878
Mozilla Foundation Security Advisory 2026-04
CVE: CVE-2026-0878
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 147
Mozilla
Mozilla Foundation Security Advisory 2026-01: CVE-2026-0878
vendor_mozilla·CVSS 8.0
CVE-2026-0878 [HIGH] Mozilla Foundation Security Advisory 2026-01: CVE-2026-0878
Mozilla Foundation Security Advisory 2026-01
CVE: CVE-2026-0878
Product: Firefox
Impact: moderate
Fixed in: Firefox 147
Mozilla
Mozilla Foundation Security Advisory 2026-03: CVE-2026-0878
vendor_mozilla·CVSS 8.0
CVE-2026-0878 [HIGH] Mozilla Foundation Security Advisory 2026-03: CVE-2026-0878
Mozilla Foundation Security Advisory 2026-03
CVE: CVE-2026-0878
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.7
Mozilla
Mozilla Foundation Security Advisory 2026-05: CVE-2026-0878
vendor_mozilla·CVSS 8.0
CVE-2026-0878 [HIGH] Mozilla Foundation Security Advisory 2026-05: CVE-2026-0878
Mozilla Foundation Security Advisory 2026-05
CVE: CVE-2026-0878
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.7
No detection rules found.
No public exploits indexed.
Wiz
CVE-2026-0878 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 8.0
CVE-2026-0878 [HIGH] CVE-2026-0878 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-0878 :
NixOS vulnerability analysis and mitigation
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.
Source : NVD
## 8
Score
Published January 13, 2026
Severity HIGH
CNA Score 8.0
Affected Technologies
NixOS
Mozilla Firefox
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 7.8
Exploitation Probability (EPSS) N/A
Affected packages and libraries
cpe:2.3:a:mozilla:thunderbird
thunderbird
Sources
AlmaLinux 8 Severity HIGH Has Fix Added at: Feb 11, 2026
AlmaLinux 9 Severity HIGH Has Fix Added at: Jan 20, 2026
Debian 11, 12, 1
Bugzilla
CVE-2026-0878 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
bugzilla·2026-01-13·CVSS 8.0
CVE-2026-0878 [HIGH] CVE-2026-0878 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
CVE-2026-0878 firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component
Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability affects Firefox < 147 and Firefox ESR < 140.7.
Discussion:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2026:0667 https://access.redhat.com/errata/RHSA-2026:0667
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:0694 https://access.redhat.com/errata/RHSA-2026:0694
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 9
Via RHSA-2026:0924 https://access.redhat.com/errata/RHSA-2026:0924
---
This issue has been add
https://bugzilla.mozilla.org/show_bug.cgi?id=2003989https://www.mozilla.org/security/advisories/mfsa2026-01/https://www.mozilla.org/security/advisories/mfsa2026-03/https://www.mozilla.org/security/advisories/mfsa2026-04/https://www.mozilla.org/security/advisories/mfsa2026-05/https://access.redhat.com/errata/RHSA-2026:0667https://access.redhat.com/errata/RHSA-2026:0694https://access.redhat.com/errata/RHSA-2026:0924https://access.redhat.com/errata/RHSA-2026:1320https://access.redhat.com/errata/RHSA-2026:1413https://access.redhat.com/errata/RHSA-2026:1414https://access.redhat.com/errata/RHSA-2026:1415https://access.redhat.com/errata/RHSA-2026:1461https://access.redhat.com/errata/RHSA-2026:1462https://access.redhat.com/errata/RHSA-2026:1471https://access.redhat.com/errata/RHSA-2026:1487https://access.redhat.com/errata/RHSA-2026:2041https://access.redhat.com/errata/RHSA-2026:2043https://access.redhat.com/errata/RHSA-2026:2044https://access.redhat.com/errata/RHSA-2026:2047https://access.redhat.com/errata/RHSA-2026:2069https://access.redhat.com/errata/RHSA-2026:2070https://access.redhat.com/errata/RHSA-2026:2073https://access.redhat.com/errata/RHSA-2026:2074https://access.redhat.com/errata/RHSA-2026:2220https://access.redhat.com/errata/RHSA-2026:2231https://access.redhat.com/errata/RHSA-2026:2271https://access.redhat.com/errata/RHSA-2026:2286https://access.redhat.com/security/cve/CVE-2026-0878https://bugzilla.redhat.com/show_bug.cgi?id=2428965https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0878.json
2026-01-13
Published