Cyber Resilience

CVE-2026-6778

Memory Safety in Mozilla Firefox ≤ 150.0

Memory Safety
Published
21 April 2026
Modified
22 April 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS Score 0.0026 18th percentile
Risk Priority 43 floored blend · peak EPSS

Summary

CVE-2026-6778 is a medium-severity NULL Pointer Dereference (CWE-476) vulnerability in Mozilla Firefox. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked at the 18th 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.

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-2026-6778 is an invalid pointer vulnerability (CWE-476, CWE-824) in the Audio/Video: Playback component of Mozilla Firefox and Thunderbird. Published on 2026-04-21, it carries a CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). The issue was addressed in Firefox 150 and Thunderbird 150.

Unauthenticated remote attackers can exploit this vulnerability over the network with low attack complexity and without requiring user interaction or privileges. Successful exploitation results in a low-impact denial of service, such as application crashes affecting availability.

Mozilla's security advisories MFSA2026-30 and MFSA2026-33 provide details on the vulnerability and patches, recommending upgrades to Firefox 150 or Thunderbird 150. Further technical information is available in Bugzilla ticket 2022746.

OWASP Top 10 for Web (2025)

A10:2025 Mishandling of Exceptional Conditions

EU & UK References

Vulnerability Data

Invalid pointer in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CWE(s)
CWE-476CWE-824

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
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.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-16353Same product: Mozilla Firefox
CVE-2026-16409Same product: Mozilla Firefox
CVE-2026-6757Same product: Mozilla Firefox
CVE-2026-2805Same product: Mozilla Firefox
CVE-2026-2785Same product: Mozilla Firefox
CVE-2024-7652Same product: Mozilla Firefox
CVE-2026-6751Same product: Mozilla Firefox
CVE-2026-6748Same product: Mozilla Firefox
CVE-2026-12329Same product: Mozilla Firefox
CVE-2026-6749Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 150.0
mozilla
thunderbird
≤ 150.0

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (including static analysis) directly finds null-dereference bugs before deployment.

SA-15 Development Process, Standards, and Tools partial match

Documented development standards and tools can enforce null-safety rules and safe pointer usage.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles can mandate defensive coding such as explicit null checks before dereference.

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 (static analysis, code review, safe coding standards) directly prevent NULL dereference bugs during development.

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.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect NULL dereference defects before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates defensive coding practices that can prevent NULL dereferences.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify input validation and pointer-safety rules.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage defensive design that avoids unsafe pointer use.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly require NULL-pointer checks and safe dereference patterns.

References