Cyber Resilience

CVE-2026-8953

Critical

Published: 19 May 2026

Published
19 May 2026
Modified
19 May 2026
KEV Added
—
Patch
—
CVSS Score v3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
EPSS Score 0.0053 41.0th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-8953 is a critical-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 9.6 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 41.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CWE(s)
CWE-416

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
Why these techniques?

Sandbox escape via use-after-free directly enables privilege escalation from browser sandbox (T1068) and client-side code execution via exploit (T1203).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2025-1930Same product: Mozilla Firefox
CVE-2026-0884Same product: Mozilla Firefox
CVE-2026-2765Same product: Mozilla Firefox
CVE-2026-2767Same product: Mozilla Firefox
CVE-2026-2789Same product: Mozilla Firefox
CVE-2026-2763Same product: Mozilla Firefox
CVE-2026-2787Same product: Mozilla Firefox
CVE-2025-1010Same product: Mozilla Firefox
CVE-2026-2797Same product: Mozilla Firefox
CVE-2026-2769Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 115.36.0 · ≤ 151.0.0 · 140.0 — 140.11.0
mozilla
thunderbird
≤ 140.11

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

References