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Mozilla Firefox CVE-2026-74948

| EUVDEUVD-2026-60754 MEDIUM
Information Exposure (CWE-200)
2026-08-18 mozilla GHSA-v63p-fxw9-fq8j
Information Disclosure Mozilla
6.5
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
    Attacker hosts malicious webpage
  2. Delivery
    User navigates to page via phishing or redirect
  3. Exploit
    Page triggers crafted Graphics component rendering
  4. Execution
    Firefox leaks sensitive data to page context
  5. Impact
    Attacker script exfiltrates disclosed information

Vulnerability Assessment

Weakness
CWE
CWE-200
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection Data exposure prevention
MITRE ATT&CK

2 techniques across 2 tactics: Collection, Discovery

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

The user must navigate to an attacker-controlled or compromised webpage using an unpatched Firefox version (any release prior to 154, or any ESR prior to the respective fixed versions). No authentication, account, or special browser configuration is required - the vulnerability is present in default Firefox installations. Exploitation is limited by mandatory user interaction (UI:R): the victim must actively load the malicious page; drive-by exploitation without any navigation is not possible. The scope is unchanged (S:U), meaning the attacker gains information accessible within the browser's process but cannot directly affect the underlying OS or other applications. Impact is confidentiality-only - no write or availability primitive is exposed.
Impact

The CVSS 3.1 score of 6.5 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N) reflects a genuine but constrained threat: network-reachable, low-complexity exploitation with no privileges required, but mandatory user interaction limits mass exploitation. The High confidentiality impact is the most significant signal - sensitive data exposure from the Graphics subsystem could include rendered page content, cross-origin pixel data, or internal memory artifacts. EPSS places this at just 0.16% (6th percentile), consistent with the absence of public exploit code and KEV listing; this is not a vulnerability under active widespread attack. No KEV entry and no known POC confirm the current risk is theoretical rather than operational. The combination of UI:R and absence of exploit code means opportunistic mass exploitation is unlikely, but targeted campaigns against high-value browser users remain a plausible threat model. Patch availability across all affected branches removes the primary remediation barrier - the fix is straightforward and risk drops to near-zero post-upgrade.
Exploit ScenarioDerived

An attacker hosts a malicious webpage containing crafted content that triggers the vulnerable Graphics component code path when rendered by Firefox. A user browsing to the page - via phishing link, malicious ad, or compromised site - causes the browser to inadvertently expose sensitive data (potentially cross-origin rendered content or memory artifacts) that the attacker's page script can then exfiltrate. No public proof-of-concept exists at time of analysis, so replicating this attack requires independent vulnerability research.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 21, 2026

Information disclosure in Firefox's Graphics component exposes sensitive data to remote attackers who can lure users to a malicious webpage. All Firefox release channels prior to version 154 and multiple ESR branches are affected, with fixes shipping in Firefox 154, ESR 115.39, ESR 140.14, and ESR 153.1. No public exploit code has been identified and exploitation probability is very low (EPSS 0.16%), though the high confidentiality impact and zero-privilege-required attack path make patching a straightforward priority.

RemediationAI

The primary fix is to upgrade to Firefox 154 or later for standard release users. ESR users should update to Firefox ESR 115.39, ESR 140.14, or ESR 153.1 depending on their deployed branch. All patched versions are available via Mozilla's standard update mechanism and are documented across Mozilla Security Advisories mfsa2026-74 through mfsa2026-80 (https://www.mozilla.org/security/advisories/). For environments unable to patch immediately, restricting access to untrusted or external web content via network policy or proxy allowlisting reduces exposure; however, this is operationally disruptive for general-purpose browser deployments. Disabling JavaScript is a highly effective compensating control that prevents triggering Graphics component APIs via script, but renders the browser unusable for most modern web applications. Given patch availability across all affected branches, upgrade is strongly preferred over workarounds.

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Technical ContextAI · show details

The vulnerability resides in Firefox's Graphics component (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor), which handles rendering operations including canvas, WebGL, and related browser graphics APIs. These subsystems are historically susceptible to cross-origin or cross-context memory leaks when rendered output or internal state is accessible to attacker-controlled script. The affected product is identified by CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* - the wildcard version indicates all Firefox versions prior to the fix across all platforms. The ESR track breadth (115.39, 140.14, 153.1) confirms the defect spans multiple long-term support lineages, suggesting the root cause was present for an extended period.

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Severity by source

Vendor (mozilla) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
vuln.today AI 6.5 MEDIUM

Browser Graphics flaw requires only user page-visit (UI:R, PR:N, AV:N); pure information disclosure yields C:H with no integrity or availability impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
SUSE HIGH
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
None
Availability
None

Lifecycle Timeline

3
CVSS changed
Aug 21, 2026 - 21:22 NVD
6.5 (MEDIUM)
CVE Published
Aug 18, 2026 - 12:23 cve.org
MEDIUM 6.5
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Information disclosure in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
Ubiquitous
Firefox is a top-tier global browser deployed across hundreds of millions of endpoints.
Data Quality
6 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS 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 0.2%
Patch available Yes
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· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
High

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
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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Same weakness CWE-200 – Information Exposure

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Same technique Information Disclosure

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CVE-2025-68613 HIGH POC
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CVE-2015-1701 HIGH POC
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CVE-2017-0147 HIGH POC
7.5

Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/kiosk/firefox-esr:140.14-75.12 Affected
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Desktop Applications 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-74948 ADVISORY https://vuldb.com/vuln/391586 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:3658/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=2060106 REF https://www.mozilla.org/security/advisories/mfsa2026-74/ REF https://www.mozilla.org/security/advisories/mfsa2026-75/ REF https://www.mozilla.org/security/advisories/mfsa2026-76/ REF https://www.mozilla.org/security/advisories/mfsa2026-77/ REF https://www.mozilla.org/security/advisories/mfsa2026-78/ REF https://www.mozilla.org/security/advisories/mfsa2026-79/ REF https://www.mozilla.org/security/advisories/mfsa2026-80/

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