Cyber Resilience

CVE-2026-5732

Memory Safety in Mozilla Firefox ≤ 140.9.1

Published
07 April 2026
Modified
15 July 2026
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0035 28th percentile
Risk Priority 63 floored blend · peak EPSS

Summary

CVE-2026-5732 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Mozilla Firefox. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 28th 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-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-5732 is an integer overflow vulnerability caused by incorrect boundary conditions in the Graphics: Text component. It affects Mozilla Firefox prior to version 149.0.2, Firefox ESR prior to 140.9.1, Thunderbird prior to 149.0.2, and Thunderbird prior to 140.9.1. The issue is classified under CWE-190 (Integer Overflow or Wraparound).

The vulnerability carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), denoting high severity. Remote attackers with no privileges can exploit it over the network with low attack complexity, though it requires user interaction. Successful exploitation enables high-impact violations of confidentiality, integrity, and availability.

Mozilla advisories detail the fix in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1. Mitigation involves updating to these patched versions. Additional technical details are provided in Mozilla Security Advisories MFSA2026-25, MFSA2026-27, MFSA2026-28, MFSA2026-29, and Bugzilla bug 2017867.

EU & UK References

Vulnerability Data

Incorrect boundary conditions, integer overflow in the Graphics: Text component. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

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.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-11152Same product: Mozilla Firefox
CVE-2026-16395Same product: Mozilla Firefox
CVE-2025-49710Same product: Mozilla Firefox
CVE-2026-16408Same product: Mozilla Firefox
CVE-2023-5173Same product: Mozilla Firefox
CVE-2026-2774Same product: Mozilla Firefox
CVE-2026-2762Same product: Mozilla Firefox
CVE-2025-10533Same product: Mozilla Firefox
CVE-2026-6773Same product: Mozilla Firefox
CVE-2026-0880Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 140.9.1 · ≤ 149.0.2

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

Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds integer overflow defects before deployment.

Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.

Input validation enforces bounds on values before arithmetic, stopping the conditions that trigger overflow or wraparound.

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.

finds

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