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Vulnerability · Published Jan 13, 2026 · Assigned by mozilla

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

High 8.0

In plain English

A high-severity memory corruption in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.0High
Exploit odds (30 days)0.5%top 59.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10firefox140.7.0-1.el10_1ALSA-2026:2271
AlmaLinux:8firefox140.7.0-1.el8_10.alma.1ALSA-2026:0667
AlmaLinux:9firefox140.7.0-1.el9_7.alma.1ALSA-2026:0694
AlmaLinux:9firefox-x11140.7.0-1.el9_7.alma.1ALSA-2026:0694
AlmaLinux:10thunderbird140.7.0-1.el10_1.alma.1ALSA-2026:2286
AlmaLinux:8thunderbird140.7.0-1.el8_10.alma.1ALSA-2026:2220
AlmaLinux:9thunderbird140.7.0-1.el9_7.alma.1ALSA-2026:0924
Debian:12firefox-esr140.7.0esr-1~deb12u1DEBIAN-CVE-2026-0878
Debian:12firefox-esr140.7.0esr-1~deb12u1DSA-6101-1
Debian:13firefox-esr140.7.0esr-1~deb13u1DEBIAN-CVE-2026-0878
Debian:13firefox-esr140.7.0esr-1~deb13u1DSA-6101-1
Debian:14firefox-esr140.7.0esr-1DEBIAN-CVE-2026-0878
Debian:12thunderbird1:140.7.0esr-1~deb12u1DSA-6103-1
Debian:12thunderbird1:140.7.0esr-1~deb12u1DEBIAN-CVE-2026-0878
Debian:13thunderbird1:140.7.0esr-1~deb13u1DSA-6103-1
Debian:13thunderbird1:140.7.0esr-1~deb13u1DEBIAN-CVE-2026-0878
Debian:14thunderbird1:140.7.0esr-1DEBIAN-CVE-2026-0878
Rocky Linux:8firefox0:140.7.0-1.el8_10RLSA-2026:0667
Rocky Linux:9firefox0:140.7.0-1.el9_7RLSA-2026:0694
Rocky Linux:8thunderbird0:140.7.0-1.el8_10RLSA-2026:2220
Rocky Linux:9thunderbird0:140.7.0-1.el9_7RLSA-2026:0924
Ubuntu:22.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-0878
Ubuntu:24.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-0878
Ubuntu:24.04:LTSmozjs115no fix listedUBUNTU-CVE-2026-0878
Ubuntu:22.04:LTSmozjs78no fix listedUBUNTU-CVE-2026-0878
Ubuntu:22.04:LTSmozjs91no fix listedUBUNTU-CVE-2026-0878
Ubuntu:22.04:LTSthunderbird1:140.7.1+build1-0ubuntu0.22.04.1UBUNTU-CVE-2026-0878

Affected products (as reported)

VendorProductVersions
Mozilla Firefox see references
Mozilla Thunderbird see references

Weakness: CWE-119, CWE-20 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N

References