What is CVE-2026-16393?

CVE-2026-16393 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.1/10. Published 2026-07-21.

How severe is CVE-2026-16393?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Buffer overflow in Mozilla Firefox

CVE-2026-16393

Incorrect boundary conditions in the Graphics: WebGPU component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

Vulnerability class: Buffer Overflow

EPSS: 0.003 (22.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.

Affected products

Mozilla Firefox — versions 153
Mozilla Thunderbird — versions 153

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

security@mozilla.org (Permissions Required)
security@mozilla.org (Vendor Advisory)
security@mozilla.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-16393?: CVE-2026-16393 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.1/10. Published 2026-07-21.
How severe is CVE-2026-16393?: Critical severity. CVSS v3 base score is 9.1 out of 10.