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Mozilla Firefox CVE-2026-100806

| EUVDEUVD-2026-88785 MEDIUM
Use of Uninitialized Variable (CWE-457)
2026-09-29 mozilla GHSA-3pqh-hh73-fq7v
Information Disclosure Mozilla Firefox
Medium
Disputed · 4.3 Vendor: mozilla
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Attack ChainAIDerived

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

  1. Access
    Host malicious WebGPU web page
  2. Exploit
    Lure victim to visit page
  3. Execution
    Firefox WebGPU reads uninitialized memory
  4. Impact
    Trigger crash / undefined behavior

Vulnerability Assessment

Weakness
CWE
CWE-457
ASVS 5.0
V15 - Secure Coding and Architecture Variable initialization checks
Exploitation Conditions

Requires the victim to use Firefox (before 157, or ESR before 153.4) and to visit or render attacker-controlled content that exercises the Graphics: WebGPU component. WebGPU processing of the malicious content triggers a read of uninitialized memory. Exploitation is limited by mandatory user interaction (UI:R - the user must load the crafted page), the WebGPU code path being reachable, and the impact being confined to availability (crash/undefined behavior) with no vendor-confirmed confidentiality or integrity effect.
Impact

This is a genuinely low-priority issue despite the network attack vector. The Mozilla-supplied CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L) scores 4.3 and, critically, sets Confidentiality and Integrity to None with only Availability:Low - meaning the concrete outcome is a browser crash/instability, not code execution or data theft. This contradicts the 'Information Disclosure' tag: CWE-457 (uninitialized memory) can theoretically leak memory contents, but the vendor's own impact metrics (C:N) indicate no confirmed confidentiality impact, so the tag is loose/aspirational rather than substantiated. There is no EPSS score, no CISA KEV listing, and no public exploit provided - so exploitation signals are absent across the board. UI:R means a victim must actively visit attacker-controlled content, further limiting real-world risk. This is a self-reported Mozilla hardening fix bundled into a routine release, consistent with a low-severity WebGPU memory-safety cleanup rather than an actively targeted flaw.
Exploit ScenarioDerived

An attacker hosts a malicious web page containing crafted WebGPU (GPU compute/graphics) content and lures a Firefox user into visiting it. When Firefox's WebGPU component processes the content it reads uninitialized memory, most likely producing a crash or undefined rendering behavior; no public exploit code exists and confidentiality/integrity impact is rated None by the vendor.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 29, 2026

Uninitialized memory reads in the WebGPU component of Mozilla Firefox before 157 (and ESR before 153.4) can cause availability impacts such as browser crashes when a remote attacker convinces a user to load crafted content that exercises WebGPU. Exploitation requires user interaction (UI:R) and the WebGPU code path to be reachable, and the vendor-assigned CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L) limits impact to low availability with no confirmed confidentiality or integrity effect. No public exploit has been identified at time of analysis; the issue is considered low priority and was fixed in Firefox 157 and Firefox ESR 153.4 per Mozilla advisories mfsa2026-100 and mfsa2026-97.

RemediationAI

Vendor-released patch: upgrade to Firefox 157 or Firefox ESR 153.4; these versions contain the fix announced in Mozilla advisories mfsa2026-100 and mfsa2026-97 (https://www.mozilla.org/security/advisories/mfsa2026-100/ and https://www.mozilla.org/security/advisories/mfsa2026-97/). No workaround is officially documented. If immediate upgrade is not possible, as a compensating control, disable WebGPU via the dom.webgpu.enabled preference (set to false) to prevent the vulnerable code path from being exercised; this may break websites and applications that rely on WebGPU, and it does not substitute for patching. The underlying report is tracked at https://bugzilla.mozilla.org/show_bug.cgi?id=2060408.

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Technical ContextAI · show details

The vulnerability is a CWE-457 (Use of Uninitialized Variable) issue in the Graphics: WebGPU component of Firefox. WebGPU is a web standard that exposes GPU compute and rendering capabilities to web content. During processing of malicious or malformed WebGPU content, the browser reads memory that has not been initialized, which can result in undefined behavior, crashes, or potentially unintended data exposure. Mozilla's advisory and Bugzilla entry (bug 2060408) indicate the flaw was resolved in Firefox 157 and Firefox ESR 153.4. The CPE string cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* confirms Mozilla Firefox as the affected product. Although the input tags include 'Information Disclosure', the assigned CVSS vector (C:N/I:N/A:L) and the independent assessment limit the confirmed impact to low availability; any information disclosure remains unconfirmed by the vendor.

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Severity by source

Sources disagree (Medium–Critical)
Vendor (mozilla) PRIMARY 4.3 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
vuln.today AI 4.3 MEDIUM

Remote crafted web content over the network (AV:N) requires the victim to load the page (UI:R), no auth (PR:N); uninitialized-memory read yields only a crash, so A:L and C/I:N.

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

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

2
CVE Published
Sep 29, 2026 - 12:36 cve.org
UNKNOWN (no severity yet)
CVE Published
Sep 29, 2026 - 12:36 cve.org
MEDIUM 4.3

DescriptionCVE.org

Uninitialized memory in the Graphics: WebGPU component. This vulnerability was fixed in Firefox ESR 153.4 and Firefox 157.

Threat Intelligence Overview

EPSS Score
0.3%
Top 83% exploitable
Prevalence
Ubiquitous
Firefox is one of the most widely deployed desktop web browsers globally
Data Quality
5 sources
Confidence: Medium
EUVD 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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
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· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
High
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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-2026-100806 ADVISORY https://vuldb.com/vuln/411379 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2060408 REF https://www.mozilla.org/security/advisories/mfsa2026-100/ REF https://www.mozilla.org/security/advisories/mfsa2026-101/ REF https://www.mozilla.org/security/advisories/mfsa2026-103/ REF https://www.mozilla.org/security/advisories/mfsa2026-97/

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