Cyber Resilience

CVE-2026-6752

Memory Safety in Mozilla Firefox ≤ 115.35.0

Published
21 April 2026
Modified
15 July 2026
Patch / advisory
CVSS Score v3.1 7.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS Score 0.0031 23th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-6752 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Mozilla Firefox. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 23th 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-2026-6752 involves incorrect boundary conditions in the WebRTC component, classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). This vulnerability affects Mozilla Firefox prior to version 150, Firefox ESR prior to 115.35 and 140.10, Thunderbird prior to 150, and Thunderbird prior to 140.10. It carries a CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L), indicating high severity due to its network accessibility and low barriers to exploitation.

Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low attack complexity and no change in scope. Successful exploitation can result in limited impacts, including partial disclosure of sensitive information, minor modification of data, or limited denial of service.

Mozilla addressed the issue in the specified fixed versions of Firefox and Thunderbird. Security advisories MFSA2026-30 through MFSA2026-33 and Bugzilla entry 2027499 provide further details on the patches and affected releases.

EU & UK References

Vulnerability Data

Incorrect boundary conditions in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

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.
T1055 Process Injection Stealth
Adversaries may inject code into processes in order to evade process-based defenses as well as possibly 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-2026-12300Same product: Mozilla Firefox
CVE-2026-2788Same product: Mozilla Firefox
CVE-2025-8044Same product: Mozilla Firefox
CVE-2026-12309Same product: Mozilla Firefox
CVE-2026-16393Same product: Mozilla Firefox
CVE-2026-8974Same product: Mozilla Firefox
CVE-2025-4091Same product: Mozilla Firefox
CVE-2025-9185Same product: Mozilla Firefox
CVE-2026-16359Same product: Mozilla Firefox
CVE-2025-8035Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 115.35.0 · ≤ 150.0 · 140.0 — 140.10.0
mozilla
thunderbird
140.0 — 140.10.0

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)
  • V17.3.2

Mitigating Controls (NIST 800-53 r5) AI

Developer security testing and code review can discover incorrect buffer-size computations before deployment.

Secure engineering principles require memory-safe design and coding that structurally avoids buffer-boundary violations.

Input validation directly enforces bounds checking that stops out-of-bounds reads/writes from being introduced or reached.

Memory protection restricts exploitation impact of buffer overflows without eliminating the underlying coding flaw.

Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.

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 (bounds checking, safe APIs, reviews) directly prevent this class of flaw.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis directly surface buffer-boundary flaws.

ID.RA-08 partial match
prevents

Receiving and triaging vulnerability disclosures commonly includes buffer-related reports.

PR.AT-02 partial match
prevents

Developer training on secure coding reduces introduction of memory-buffer errors.

PR.PS-02 partial match
prevents

Patching replaces vulnerable code containing buffer-boundary defects.

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.

degrades

Secure coding standards directly require correct buffer-size calculations.

finds

Security testing in development catches out-of-bounds accesses before release, covering most instances of the weakness.

prevents

Secure development lifecycle mandates memory-safety practices that directly prevent buffer-boundary violations.

prevents

Application security requirements can specify memory-safety rules, but do not prescribe implementation details.

prevents

Secure architecture and engineering principles include memory-safe design patterns that mitigate buffer overflows.

References