Cyber Resilience

CVE-2026-16369

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 36th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-16369 is a critical-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 36th 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 SI-2 (Flaw Remediation) and SC-18 (Mobile Code) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Integer overflow 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 TechniquesAI

T1189 Drive-by Compromise Initial Access
Adversaries may gain access to a system through a user visiting a website over the normal course of browsing.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
Why these techniques?

Integer overflow in browser WebAssembly enables remote code execution via malicious web content, directly mapping to drive-by compromise and client-side exploitation.

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

CVEs Like This One

CVE-2026-2781Same product: Mozilla Firefox
CVE-2026-2762Same product: Mozilla Firefox
CVE-2026-8956Same product: Mozilla Firefox
CVE-2026-2774Same product: Mozilla Firefox
CVE-2026-6783Same product: Mozilla Firefox
CVE-2026-0880Same product: Mozilla Firefox
CVE-2026-16402Same product: Mozilla Firefox
CVE-2026-8949Same product: Mozilla Firefox
CVE-2026-16389Same product: Mozilla Firefox
CVE-2026-2790Same 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)
  • V5.2.6

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly requires timely application of vendor patches that remediate the integer overflow in the WebAssembly engine.

SC-18 Mobile Code partial match
prevent

Controls execution of untrusted mobile code (JavaScript/WebAssembly) that triggers the integer overflow.

prevent

Enforces memory protections that block exploitation of the integer overflow leading to code execution.

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 mostly match
prevents

Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.

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.

detects

Security testing in development can detect integer overflows before release.

prevents

Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.

degrades

Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.

degrades

Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.

prevents

Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.

References