CVE-2026-74936
Use-after-free in Firefox/Thunderbird WebAssembly allows remote code execution via web content.
Is CVE-2026-74936 being exploited?
Not confirmed. CVE-2026-74936 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 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-74936?
CVE-2026-74936 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-2026-74936?
Yes. A fix has been recorded for CVE-2026-74936. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-74936 affect?
CVE-2026-74936 affects Mozilla Firefox <154, Firefox ESR <140.14, Firefox ESR <153.1, Mozilla Thunderbird <154, and 2 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-74936?
Update to Firefox/Thunderbird 154 or ESR 140.14/153.1; apply vendor patches immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution or sandbox escape by processing crafted WebAssembly/JS, enabling arbitrary code execution or browser compromise.
Immediate action required