CVE-2026-0881: Sandbox escape in the Messaging System component

Critical severity · published Jan 13, 2026

CVE-2026-0881

Sandbox escape in the Messaging System component

10.0

CVSS

0.3%

EPSS

On KEV

Description

Sandbox escape in the Messaging System component. This vulnerability was fixed in Firefox 147 and Thunderbird 147.

CVSS vector

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.3% · higher than 28% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

Firefox · Mozilla

before 147.0 · source: NVD

Thunderbird · Mozilla

before 147.0 · source: NVD

Affected product

Firefox

Mozilla

All Firefox CVEs

References

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-0881

CVE.org

https://www.cve.org/CVERecord?id=CVE-2026-0881

Permissions Required

https://bugzilla.mozilla.org/show_bug.cgi?id=2005845

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026-01/

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026-04/

access.redhat.com

https://access.redhat.com/security/cve/CVE-2026-0881

bugzilla.redhat.com

https://bugzilla.redhat.com/show_bug.cgi?id=2428970

security.access.redhat.com

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0881.json