Vulnerability · Published Jan 13, 2026 · Assigned by mozilla
CVE-2026-0881Sandbox escape in the Messaging System component
Critical 10.0
In plain English
A critical-severity improper access control 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 0.3% (higher than 29% of all known vulnerabilities).
Severity (CVSS 3.1)10.0Critical
Exploit odds (30 days)0.3%top 71.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Sandbox escape in the Messaging System component. This vulnerability was fixed in Firefox 147 and Thunderbird 147.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-0881 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-0881 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-0881 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-0881 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-0881 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-0881 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-693, CWE-284 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2005845
- https://www.mozilla.org/security/advisories/mfsa2026-01/
- https://www.mozilla.org/security/advisories/mfsa2026-04/
- https://access.redhat.com/security/cve/CVE-2026-0881 vdb-entry, x_refsource_REDHAT
- RHBZ#2428970 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0881.json x_sadp-csaf-vex