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Mozilla Firefox CVE-2026-100761

| EUVDEUVD-2026-88913 HIGH
Use After Free (CWE-416)
2026-09-29 mozilla GHSA-h4g9-2fvm-v2j2
Privilege Escalation Use After Free Memory Corruption Red Hat Mozilla Firefox
8.8
CVSS 3.1 · Vendor: mozilla
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Lure victim to malicious page
  2. Delivery
    Deliver crafted WebGPU content
  3. Exploit
    Trigger use-after-free in WebGPU
  4. Execution
    Corrupt heap / reclaim freed object
  5. Impact
    Execute attacker-controlled code

Vulnerability Assessment

Weakness
CWE
CWE-416
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Requires the victim to use an affected Firefox version (before 157) and to visit/render attacker-controlled web content that exercises the Graphics: WebGPU component; per CVSS UI:R, user interaction (navigating to the malicious page) is mandatory, which limits mass automated exploitation (SSVC Automatable: no). Exploitation further depends on WebGPU being reachable/enabled in the target build, and reliable code execution requires per-target heap manipulation to reclaim the freed object. No authentication is required (PR:N).
Impact

The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H = 8.8 High) describes a network-reachable, low-complexity, unauthenticated memory-corruption flaw requiring only user interaction (visiting a malicious page), with total confidentiality/integrity/availability impact - a profile typical of a browser use-after-free. This is corroborated by CISA's SSVC decision: Technical Impact 'total' matches the C:H/I:H/A:H, but Exploitation is 'none' (no observed exploitation) and Automatable is 'no' (the required user interaction and per-target heap-grooming defeat mass automation). No EPSS score, no CISA KEV listing, and no public POC were provided, so despite the high base score there is no evidence of real-world exploitation at this time. The realistic posture is a serious-but-not-emergency browser bug: high theoretical impact, patched by the vendor, but currently unexploited and not trivially weaponizable at scale. WebGPU is also not enabled/reachable in every deployment, which narrows the practical attack surface further. No conflicting signals in the data - the CVSS network/UI:R profile is fully consistent with a drive-by browser exploit.
Exploit ScenarioDerived

An attacker hosts a malicious web page containing crafted WebGPU (GPU compute/graphics) content and lures a Firefox user (pre-157) to visit it. Triggering the use-after-free in the Graphics: WebGPU component corrupts heap memory, potentially leading to code execution in the content process. No public exploit code was identified at time of analysis, and CISA SSVC rates exploitation as 'none'.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 29, 2026

A use-after-free in Mozilla Firefox's Graphics: WebGPU component (CWE-416) lets a remote attacker who gets a victim to render attacker-controlled web content corrupt memory and potentially achieve code execution in the browser's process, earning a High-severity CVSS 3.1 score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). All Firefox builds prior to 157 are affected, and Mozilla fixed the issue in Firefox 157 (advisory mfsa2026-97, Bugzilla 2059020). No public exploit code or confirmed active exploitation has been identified at time of analysis, and because the vector requires user interaction, mass automated exploitation is unlikely, though per-target heap grooming is needed for reliable execution.

RemediationAI

Vendor-released patch: Firefox 157 - upgrade to Firefox 157 or later; the update is delivered through Firefox's built-in updater and can be forced via Help > About Firefox, and enterprise deployments should push 157 through their normal update channel. If immediate upgrade is not possible, disabling or restricting the WebGPU feature in the affected build removes the attack surface for this specific flaw, at the cost of breaking WebGPU-based web applications and games for users; because the vector requires user interaction with a malicious page, additional temporary hardening such as tightening web-content trust policies or isolating high-risk browsing reduces exposure but does not eliminate the underlying memory-safety bug. Detailed fix information and affected-version confirmations are in Mozilla's advisory at https://www.mozilla.org/security/advisories/mfsa2026-97/. There is no indication of active exploitation, so risk-based prioritization around normal patch cycles is reasonable.

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Technical ContextAI · show details

The flaw is a use-after-free (CWE-416) inside Firefox's Graphics: WebGPU implementation, the browser subsystem that exposes the WebGPU API for GPU-accelerated rendering and compute from JavaScript. In a use-after-free, an object is freed while a stale reference to it remains, and an attacker who can control the timing and content of allocations after the free may reclaim that memory with attacker-influenced data, turning the dangling reference into a controlled read/write primitive that can be leveraged toward code execution within the compromised browser process. The CVSS vector (AV:N/AC:L/PR:N/UI:R) confirms the bug is network-reachable, low complexity, and needs no authentication, but requires the victim to interact with attacker-controlled content and the WebGPU path to be reachable in the target build, which matches the CISA SSVC assessment of Exploitation: none and Automatable: no.

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Severity by source

Vendor (mozilla) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 8.8 HIGH

Remote drive-by via malicious web page (AV:N, PR:N) needs the user to load the page (UI:R); a WebGPU use-after-free yields full memory-corruption impact (C/I/A:H) within the content process (S:U).

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE CRITICAL
Red Hat 7.5 HIGH

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
CVSS changed
Sep 29, 2026 - 14:22 NVD
8.8 (HIGH)
CVE Published
Sep 29, 2026 - 12:35 cve.org
HIGH 8.8
CVE Published
Sep 29, 2026 - 12:35 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Privilege escalation due to use-after-free in the Graphics: WebGPU component. This vulnerability was fixed in Firefox 157.

Executive ViewAI

Why It Matters

Mozilla Firefox versions prior to 157 contain a high-severity use-after-free in the WebGPU graphics component that could allow an unauthenticated remote attacker to run code in the browser process when a user renders attacker-controlled web content. This affects any employee or system using unpatched Firefox for web browsing, creating a risk of endpoint compromise or data theft from a malicious or compromised website. No public exploit identified at time of analysis, and exploitation requires user interaction, but the broad install base and potential code-execution impact justify prioritized remediation.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.2%
Top 86% exploitable
Prevalence
Ubiquitous
Firefox is one of the most widely deployed desktop web browsers globally
Data Quality
7 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS Vulnrichment Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Privilege Escalation HIGH

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Use After Free HIGH

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Affected Products (CPE)CVE.org

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-100761 ADVISORY https://vuldb.com/vuln/411331 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2059020 REF https://www.mozilla.org/security/advisories/mfsa2026-101/ REF https://www.mozilla.org/security/advisories/mfsa2026-97/

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