Widely used Firefox; sandbox escape could lead to host compromise; critical 10.0 risk.
CVE-2026-0881
Firefox Messaging System sandbox escape; could escape sandbox (<147).
Is CVE-2026-0881 being exploited?
Not confirmed. CVE-2026-0881 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-0881?
CVE-2026-0881 is rated Critical with a CVSS score of 10.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-0881?
Yes. A fix has been recorded for CVE-2026-0881. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-0881 affect?
CVE-2026-0881 affects Mozilla Firefox < 147. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-0881?
Upgrade Firefox to 147+; apply latest patches
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via sandbox escape in Firefox <147.
Immediate action required