Security Resilience

CVE-2026-8091

Mozilla Firefox ≤ 115.35.2

Published
07 May 2026
Modified
11 August 2026
Patch / advisory
View 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 0.0060 47th percentile
Risk Priority 72 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-2026-8091 is a critical-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 47th 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 SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A10:2025 Mishandling of Exceptional Conditions

EU & UK References

Vulnerability Data

Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, Thunderbird 140.10.1, and Firefox ESR 115.35.2.

CWE(s)
NVD-CWE-noinfoCWE-754CWE-805

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1003.001 LSASS Memory Credential Access
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1008 Fallback Channels Command And Control
Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-4694Same product: Mozilla Firefox
CVE-2026-6772Same product: Mozilla Firefox
CVE-2025-10532Same product: Mozilla Firefox
CVE-2026-6766Same product: Mozilla Firefox
CVE-2025-14322Same product: Mozilla Firefox
CVE-2026-2801Same product: Mozilla Firefox
CVE-2026-4689Same product: Mozilla Firefox
CVE-2026-16353Same product: Mozilla Firefox
CVE-2026-6751Same product: Mozilla Firefox
CVE-2026-6748Same product: Mozilla Firefox

Affected Assets

mozilla
firefox
≤ 115.35.2 · 140.0 — 140.10.1
mozilla
thunderbird
140.0 — 140.10.1

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)
  • V1.4.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation explicitly exercises unusual conditions to find missing or incorrect checks.

SI-10 Information Input Validation good match

Input validation directly requires checking for unexpected or malformed conditions before they propagate.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles include structured handling of edge cases and exceptions during design.

SI-16 Memory Protection partial match

Memory protection mechanisms limit the blast radius when an incorrect length value causes an out-of-bounds access.

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.

ID.RA-01 partial match
blocks

Vulnerability identification can discover buffer-length flaws but does not prevent their introduction.

PR.PS-06 partial match
blocks

Secure SDLC practices directly prevent incorrect-length buffer operations via safe APIs, reviews, and testing.

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.6.4 Disciplinary process partial match
removes
A.8.15 Logging partial match
finds

Logging can record unhandled exceptions but does not prevent the weakness itself.

A.8.16 Monitoring activities partial match
finds

Monitoring may detect symptoms of unhandled conditions but does not eliminate the root weakness.

A.8.2 Privileged access rights partial match
removes
A.8.25 Secure development life cycle partial match
blocks

Secure development life cycle mandates exception handling and input validation that directly prevent missing checks for unusual conditions.

A.8.26 Application security requirements partial match
blocks

Application security requirements explicitly call for handling of exceptional conditions and error paths.

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-754, a class-level weakness. Rules are authored against its narrower children: CWE-354.

References