CVE-2026-74990
Memory-corruption in Thunderbird/Firefox enabling potential remote code execution.
Is CVE-2026-74990 being exploited?
Not confirmed. CVE-2026-74990 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 0.53% probability of exploitation in the next 30 days.
How severe is CVE-2026-74990?
CVE-2026-74990 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-2026-74990?
Yes. A fix has been recorded for CVE-2026-74990. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74990 affect?
CVE-2026-74990 affects Thunderbird 153, Thunderbird ESR 153.0, Thunderbird ESR 140.13, Firefox 153 and earlier, and 1 further product or version. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74990?
Apply vendor updates immediately to fixed releases (Thunderbird 154/153.1, ESR 140.14/153.1; Firefox 154/ESR fixes).
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted email or web content; attacker can execute arbitrary code and potentially fully compromise user systems.
Immediate action required