Cyber Resilience

CVE-2026-16363

Memory Safety in Mozilla Firefox ≤ 140.13.0

Published
21 July 2026
Modified
24 July 2026
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0044 37th percentile
Risk Priority 71 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-16363 is a critical-severity Incorrect Calculation (CWE-682) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 37th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-16355Same product: Mozilla Firefox
CVE-2019-11707Same product: Mozilla Firefox
CVE-2026-2796Same product: Mozilla Firefox
CVE-2026-16410Same product: Mozilla Firefox
CVE-2025-14325Same product: Mozilla Firefox
CVE-2026-74956Same product: Mozilla Firefox
CVE-2026-16392Same product: Mozilla Firefox
CVE-2025-14330Same product: Mozilla Firefox
CVE-2026-16362Same product: Mozilla Firefox
CVE-2025-1010Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 140.13.0 · ≤ 153.0.0
mozilla
thunderbird
≤ 140.13.0 · 141.0 — 153.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V15.2.2
  • V1.5.2
  • V3.2.3
  • V15.3.5

Mitigating Controls (NIST 800-53 r5) AI

Developer testing and evaluation directly exercises calculations and can discover incorrect or unintended results used in security decisions.

Requiring documented development processes and standards can enforce coding rules and tool usage that reduce introduction of calculation errors.

Engineering principles applied during design and implementation can require verified algorithms and safe arithmetic that structurally avoid incorrect calculation results.

Memory-protection controls limit the blast radius when a type-confusion access occurs but do not stop the flaw itself.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 partial match
prevents

Secure SDLC practices directly prevent incorrect calculations via reviews, testing, and verification in security-critical code.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Secure development lifecycle mandates verification steps that catch incorrect calculations before they reach production.

prevents

Application security requirements can explicitly call for numeric accuracy and bounds checking.

degrades

Secure architecture principles include input validation and safe arithmetic design that reduce calculation errors.

prevents

Secure coding standards directly prohibit unsafe arithmetic and require defensive checks against incorrect results.

finds

Security testing in development and acceptance can detect calculation flaws before deployment.

References