What is CVE-2026-16367?

CVE-2026-16367 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 10.0/10. Published 2026-07-21.

How severe is CVE-2026-16367?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Buffer overflow in Mozilla Firefox

CVE-2026-16367

Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

Vulnerability class: Buffer Overflow

Published 2026-07-21 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (30.3th percentile), scored 2026-10-23.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Mozilla Firefox — versions 153
Mozilla Thunderbird — versions 153

Weakness classification (CWE)

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
www.mozilla.org/security/advisories/mfsa2026-68/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2026-71/ (Vendor Advisory)

Frequently asked questions

What is CVE-2026-16367?: CVE-2026-16367 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 10.0/10. Published 2026-07-21.
How severe is CVE-2026-16367?: Critical severity. CVSS v3 base score is 10.0 out of 10.