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Firefox EUVDEUVD-2026-60686

| CVE-2026-74966 HIGH
Exposure of Private Personal Information to an Unauthorized Actor (CWE-359)
2026-08-18 mozilla GHSA-79c9-ggp3-hgmx
7.5
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 web page
  2. Delivery
    Victim visits page in unpatched Firefox
  3. Exploit
    Form Autofill component incorrectly exposes stored profile data
  4. Execution
    Attacker script reads personal information
  5. Impact
    Sensitive user data exfiltrated to attacker-controlled infrastructure

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V14 - Data Protection PII protection
Exploitation Conditions

Any Firefox installation prior to version 154 (or ESR prior to 153.1) is in scope when the user has stored data in Firefox's Form Autofill system, which is enabled by default in standard consumer installations. The CVSS vector (AV:N/AC:L/PR:N/UI:N) as submitted by Mozilla indicates no special server-side configuration, authentication, or explicit user interaction is required. Exploitation is naturally bounded by autofill content: users who have never saved autofill profiles have no sensitive data exposed through this path. Firefox deployments with Form Autofill explicitly disabled via enterprise policy (AutofillAddressEnabled=false, AutofillCreditCardEnabled=false) are not vulnerable.

Impact

The CVSS 7.5 High rating is driven by a network-accessible, unauthenticated, low-complexity vector with no user interaction required and high confidentiality impact, representing a worst-case autofill disclosure scenario. Against this, the EPSS score of 0.14% at the 4th percentile signals very low near-term exploitation probability relative to other tracked CVEs, and the absence of a CISA KEV entry means active exploitation has not been confirmed by any authoritative body. The disconnect between the high CVSS and low EPSS suggests this is a credible but presently untargeted vulnerability - typical of browser disclosure issues that require non-trivial reverse engineering to weaponize reliably. The value of Form Autofill data (personal identifiers, addresses, potentially payment card details) makes this attractive to data-harvesting actors if a reliable exploit were developed, so organizations managing large Firefox deployments should prioritize this fix within their standard patch cycle rather than treating it as an emergency. No conflicting signals are present in the available data; the CVSS UI:N claim is noted as potentially optimistic for a browser-context disclosure but is taken from the vendor-submitted vector.

Exploit ScenarioDerived

A threat actor hosts a malicious or compromised web page designed to trigger the Form Autofill disclosure bug when loaded by a Firefox user with saved autofill data. The attacker's page-level script accesses or exfiltrates personal profile data - names, addresses, or payment details - stored in the browser's autofill store, without requiring the user to take any explicit action beyond visiting the page. No public exploit code has been identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 20, 2026

Information disclosure in Firefox's Form Autofill component exposes sensitive personal data stored by the browser to unauthorized actors via a network-accessible, unauthenticated attack path scored CVSS 7.5 (AV:N/AC:L/PR:N/UI:N/C:H). All Firefox versions prior to 154 and Firefox ESR versions prior to 153.1 are affected, with Mozilla issuing four separate security advisories (mfsa2026-74, mfsa2026-77, mfsa2026-78, mfsa2026-80) across release channels. No public exploit or CISA KEV listing has been identified at time of analysis, and the EPSS exploitation probability stands at 0.14% (4th percentile).

RemediationAI

Upgrade to Firefox 154 or later, or Firefox ESR 153.1 or later, which are the vendor-confirmed patched releases per Mozilla advisories mfsa2026-74 and mfsa2026-77 (https://www.mozilla.org/security/advisories/mfsa2026-74/ and https://www.mozilla.org/security/advisories/mfsa2026-77/). Enterprise deployments that cannot update immediately should disable Form Autofill via Firefox enterprise policy by setting AutofillAddressEnabled and AutofillCreditCardEnabled to false - note this removes autofill convenience for end users and may increase help-desk load. Separately, clearing existing stored autofill profiles (Firefox Preferences > Privacy & Security > Saved Addresses and Payment Methods) eliminates the sensitive data at risk prior to patching, though this results in irreversible loss of stored profile data for users.

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Technical ContextAI · show details

CWE-359 (Exposure of Private Personal Information to an Unauthorized Actor) identifies the root cause as improper handling of user-supplied private data within the Form Autofill subsystem. Firefox's Form Autofill feature stores profile data - including names, addresses, and potentially payment card information - and the vulnerability allows this data to be read or transmitted to an unauthorized party. The affected product per CPE is cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*, covering all Firefox versions across standard and ESR release channels prior to the fix versions. The issuance of four MFSA identifiers suggests the patch was applied across multiple active release trains simultaneously, which is consistent with Mozilla's practice for high-severity browser disclosures.

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Severity by source

Vendor (mozilla) PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 6.5 MEDIUM

Browser autofill disclosure requires a victim to visit a malicious page, supporting UI:R over the vendor-submitted UI:N; no integrity or availability impact applies.

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 6.1 MEDIUM

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

3
CVSS changed
Aug 20, 2026 - 18:22 NVD
7.5 (HIGH)
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)
CVE Published
Aug 18, 2026 - 12:23 cve.org
HIGH 7.5

DescriptionCVE.org

Information disclosure in the Form Autofill component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

Executive ViewAI

Why It Matters

Firefox Form Autofill contains an unauthenticated network-accessible information disclosure vulnerability (CVE-2026-74966, CVSS 7.5) affecting all Firefox versions prior to 154 and Firefox ESR prior to 153.1, potentially exposing stored payment cards, passwords, and personal data to remote attackers without user interaction. No vendor patch has been released, though exploitation probability remains negligible (EPSS 0.14%, no active exploitation observed), giving organizations a window to implement interim protections. Organizations must inventory affected Firefox deployments and disable autofill functionality organization-wide to prevent credential exposure.

Business Impact: High
Compensating Controls

Disable Form Autofill via Firefox configuration policy or Group Policy Objects; enforce mandatory use of enterprise password management solutions with centralized audit logging; conduct an inventory of sensitive data types (payment cards, social security numbers, credentials) potentially stored in affected Firefox instances to assess breach scope; implement network monitoring for exploitation patterns targeting Firefox; establish credential rotation protocols for any accounts with autofill exposure; maintain continuous monitoring of Mozilla security advisories mfsa2026-74, mfsa2026-77, mfsa2026-78, and mfsa2026-80 for patch status updates.

Threat Intelligence Overview

EPSS Score
0.1%
Top 96% exploitable
Prevalence
Ubiquitous
Firefox is deployed across hundreds of millions of consumer and enterprise endpoints globally
Data Quality
6 sources
Confidence: High

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 0.1%
Patch available Yes
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· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

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:*:*:*:*:*:*:*:*
CVE-2015-4495 HIGH POC
8.8 Aug 08

The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote

CVE-2013-1690 HIGH POC
8.8 Jun 26

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before

CVE-2013-0758 CRITICAL POC
9.3 Jan 13

Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderb

CVE-2013-0753 CRITICAL POC
9.3 Jan 13

Use-after-free vulnerability in the serializeToStream implementation in the XMLSerializer component in Mozilla Firefox b

CVE-2012-3993 CRITICAL POC
9.3 Oct 10

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbi

CVE-2013-1710 CRITICAL POC
10.0 Aug 07

The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo

CVE-2017-3823 HIGH POC
8.8 Feb 01

An issue was discovered in the Cisco WebEx Extension before 1.0.7 on Google Chrome, the ActiveTouch General Plugin Conta

CVE-2014-8636 HIGH POC
7.5 Jan 14

The XrayWrapper implementation in Mozilla Firefox before 35.0 and SeaMonkey before 2.32 does not properly interact with

CVE-2013-0757 CRITICAL POC
9.3 Jan 13

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbi

CVE-2014-1510 CRITICAL POC
9.8 Mar 19

The Web IDL implementation in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and Se

CVE-2014-1511 CRITICAL POC
9.8 Mar 19

Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25 allow remo

CVE-2013-0643 HIGH
8.8 Feb 27

The Firefox sandbox in Adobe Flash Player before 10.3.183.67 and 11.x before 11.6.602.171 on Windows and Mac OS X, and b

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

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