Affects widely used Firefox/Thunderbird; CVSS 9.8; high-risk mitigation bypass.
CVE-2026-6768
Mitigation bypass in Firefox/Thunderbird cookies component.
Is CVE-2026-6768 being exploited?
Not confirmed. CVE-2026-6768 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 0.29% probability of exploitation in the next 30 days.
How severe is CVE-2026-6768?
CVE-2026-6768 is rated Critical with a CVSS score of 9.8. 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-2026-6768?
Yes. A fix has been recorded for CVE-2026-6768. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-6768 affect?
CVE-2026-6768 affects Firefox, Thunderbird. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-6768?
Update to Firefox 150 and Thunderbird 150 immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Bypasses cookie mitigations in Firefox/Thunderbird, enabling potential session hijacking or cookie misuse.
Immediate action required