High-severity privilege escalation in widely used Mozilla products (Firefox/Thunderbird); affects many users and should be escalated across IT teams.
CVE-2026-100824
Privilege escalation in Mozilla Places (Firefox/Thunderbird).
Is CVE-2026-100824 being exploited?
Not confirmed. CVE-2026-100824 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 0.24% probability of exploitation in the next 30 days.
How severe is CVE-2026-100824?
CVE-2026-100824 is rated High with a CVSS score of 8.8. 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-2026-100824?
Yes. A fix has been recorded for CVE-2026-100824. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-100824 affect?
CVE-2026-100824 affects Mozilla Firefox < 157, Firefox ESR < 153.4, Mozilla Thunderbird < 157, Thunderbird ESR < 153.4. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-100824?
Upgrade to Firefox 157 / ESR 153.4 and Thunderbird 157 / ESR 153.4 immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Local privilege escalation via the Places component allowing attackers to gain elevated privileges and access or modify user profile data.
Patch when possible