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Mozilla Firefox CVE-2026-74945

| EUVDEUVD-2026-60752 MEDIUM
Information Exposure (CWE-200)
2026-08-18 mozilla GHSA-5p4q-w2w4-c9jw
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 crafted page with malicious text content
  2. Delivery
    Victim user visits page in unpatched Firefox
  3. Exploit
    Graphics:Text component processes crafted input
  4. Execution
    Memory contents exposed to renderer
  5. Impact
    Attacker receives leaked sensitive data

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

Exploitation requires a victim user running an unpatched Firefox version to interact with attacker-controlled content - for example, visiting a crafted web page or rendering a document containing specially constructed text. The CVSS vector PR:N confirms no attacker authentication is required, while UI:R confirms passive server-side exploitation is not possible; the user must take an action such as browsing to the malicious resource. No special non-default Firefox configuration is indicated by the description or CVSS AC:L rating. Exploitation is limited by the user-interaction requirement, the unchanged scope (impact contained to the Firefox process), and the absence of an integrity or availability component, meaning the attacker can only read data - not modify it or crash the browser. All three ESR branches and the main release are affected, so any unpatched Firefox deployment regardless of channel is in scope.
Impact

CVSS 3.1 scores this at 6.5 Medium with vector AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N, indicating network-reachable exploitation requiring only user interaction (e.g., visiting a malicious page), with high confidentiality impact but no integrity or availability consequences. Despite the C:H rating, real-world risk signals are subdued: EPSS probability is 0.20% at the 10th percentile, KEV status is negative, and no public POC has been identified. The UI:R requirement meaningfully reduces exploitability relative to a fully passive attack. The unchanged scope (S:U) means the impact is confined to the Firefox process itself - no sandbox escape or cross-origin chain is implied by the available data. The discrepancy between the high CVSS confidentiality score and very low EPSS suggests this is a lower-priority patching target in most environments unless the organization handles highly sensitive data within Firefox sessions or runs ESR branches that lag behind the fix.
Exploit ScenarioDerived

An attacker crafts a web page or embeds content that triggers Firefox's Graphics: Text rendering path with inputs designed to expose uninitialized or out-of-bounds memory. When a victim user visits the page or views the embedded content, the browser leaks memory data back to the attacker - potentially exposing sensitive in-process information such as session tokens, cached credentials, or other browser memory contents. No public POC exists at time of analysis, so this scenario remains theoretical but is plausible given the network delivery vector and low attack complexity.
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: Text rendering component allows a remote unauthenticated attacker to leak sensitive memory contents when a user visits or interacts with crafted content. All Firefox release channels are affected, spanning the main release (pre-154) and three ESR branches (pre-115.39, pre-140.14, pre-153.1). No public exploit code exists and EPSS exploitation probability sits at just 0.20% (10th percentile), suggesting low real-world exploitation activity despite the high confidentiality impact scored by CVSS.

RemediationAI

Upgrade to Firefox 154 or later for users on the standard release channel. ESR users should upgrade to Firefox ESR 115.39, Firefox ESR 140.14, or Firefox ESR 153.1 depending on their deployed branch. These are vendor-released patches confirmed across multiple Mozilla Security Advisories (mfsa2026-74 through mfsa2026-80). If immediate upgrading is not feasible in managed enterprise environments, consider restricting user browsing to trusted internal sites via proxy policy, or deploying Firefox policy settings to disable JavaScript rendering of complex text content - however, these workarounds carry significant usability trade-offs and are not a substitute for patching. The Bugzilla tracker at https://bugzilla.mozilla.org/show_bug.cgi?id=2057808 may provide additional technical detail for patch validation.

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Technical ContextAI · show details

The vulnerability resides in Firefox's Graphics: Text subsystem - the component responsible for processing and rendering text via graphics pipelines. CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) indicates the root cause is an information leakage rather than memory corruption; likely a failure to sanitize, zero-initialize, or bound-check memory regions used during text rendering operations, resulting in unintended exposure of process memory contents to potentially untrusted rendering contexts. The affected product is identified via CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*, covering all Firefox versions on all platforms up to the fixed releases. The breadth of affected ESR branches (115.x, 140.x, and 153.x) indicates the flaw spans multiple major development generations of the browser engine.

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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

Network delivery via browser, no attacker auth needed, user must visit page (UI:R), disclosure-only with no write or crash 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 - 20:22 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: Text 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 90% exploitable
Prevalence
High
Firefox is a widely deployed browser across enterprise and consumer environments globally.
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
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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-2026-74945 ADVISORY https://vuldb.com/vuln/391585 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:3658/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=2057808 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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