What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 10.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-13 · updated 2026-07-15
• Weakness: CWE-284

Description

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

Affected products

• Mozilla Firefox: before 147.0 — fixed in 147.0
• Mozilla Thunderbird: before 147.0 — fixed in 147.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 147.0; Mozilla Thunderbird 147.0. Check the vendor advisory for mitigations.

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
• https://bugzilla.redhat.com/show_bug.cgi?id=2428970
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0881.json

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