Affects widely-used browser products (Firefox/Thunderbird); high user exposure; critical risk.
CVE-2026-8091
Memory boundary issue in browser Audio/Video playback; may crash or allow code execution.
Is CVE-2026-8091 being exploited?
Not confirmed. CVE-2026-8091 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 0.47% probability of exploitation in the next 30 days.
How severe is CVE-2026-8091?
CVE-2026-8091 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-2026-8091?
Yes. A fix has been recorded for CVE-2026-8091. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What should I do about CVE-2026-8091?
Update to Firefox 150+/Thunderbird 150+ (ESR 140.10.1/115.35.2).
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Memory corruption via media playback could crash the browser or enable arbitrary code execution.
Patch when possible