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Mozilla Firefox CVE-2026-74964

| EUVDEUVD-2026-60662 CRITICAL
Integer Overflow or Wraparound (CWE-190)
2026-08-18 mozilla GHSA-7p8c-3v22-58jp
Buffer Overflow Integer Overflow Red Hat Mozilla Suse
Critical
Disputed · 9.8 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 graphics content
  3. Exploit
    Trigger integer overflow in Graphics
  4. Execution
    Cause out-of-bounds heap write
  5. Impact
    Execute code in content process

Vulnerability Assessment

Weakness
CWE
CWE-190
ASVS 5.0
V15 - Secure Coding and Architecture Integer overflow checks
MITRE ATT&CK

1 technique across 1 tactic: Execution

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 the victim to render attacker-controlled web content in an unpatched Firefox (before 154, or ESR before 140.14/153.1) - i.e., visiting a malicious or compromised web page or loading malicious embedded content such as a crafted image, canvas, or WebGL asset that reaches the vulnerable Graphics code path. Although the supplied CVSS vector states UI:N, the practical limiting factor is that the user must open the malicious content; no authentication is required (PR:N) and attack complexity is low (AC:L). Any successful code execution is expected to occur inside Firefox's sandboxed content process, so a separate sandbox escape would be needed for full host compromise.
Impact

The provided CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, base 9.8) rates this as critical and network-exploitable without privileges or user interaction, but the UI:N metric is questionable for a browser rendering bug: exploitation realistically requires the victim to load attacker-controlled web content, which is user interaction (UI:R) and typically lowers the effective score to ~8.8. No EPSS score was supplied and the CVE is absent from CISA KEV, so there is no evidence of active exploitation; combined with no known public POC, real-world urgency is driven by Firefox's large install base and the severity of graphics memory corruption rather than by observed attacks. This should still be patched promptly - even a mid-sized enterprise or municipal IT team should treat a critical browser memory-corruption fix as high priority - but it does not currently show the hallmarks (KEV listing, high EPSS, published exploit) of an issue under mass exploitation. Note the missing EPSS and the UI:N/UI:R discrepancy as gaps to verify against the Mozilla advisories.
Exploit ScenarioDerived

An attacker hosts a malicious web page containing crafted graphics content that triggers the integer overflow when Firefox renders it, and lures a victim to visit the page via phishing or a malicious ad. The overflow leads to an undersized buffer and out-of-bounds write, corrupting heap memory to achieve code execution in the content process. No public POC is currently known, and given AC:L the trigger is reliable once the victim loads the content.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 19, 2026

Memory corruption in Mozilla Firefox's Graphics component stems from an integer overflow (CWE-190) that can be triggered when the browser processes malicious web content, potentially leading to remote code execution within the content process. The flaw affects Firefox before 154 and the ESR 140.x and 153.x branches, and Mozilla has shipped fixes across advisories MFSA2026-74 through MFSA2026-80. No public exploit has been identified at time of analysis, and the issue is not listed in CISA KEV.

RemediationAI

Vendor-released patch: upgrade to Firefox 154, Firefox ESR 140.14, or Firefox ESR 153.1 depending on your release channel, per Mozilla advisories MFSA2026-74/76/77/78/79/80 (https://www.mozilla.org/security/advisories/mfsa2026-74/). Because Firefox auto-updates by default, ensure the update service is enabled and force a restart of the browser to apply the fix across managed fleets; for enterprise deployments use the ESR branch and push the patched build via your management tooling. If patching must be delayed, compensating controls include restricting browsing to trusted sites and enabling stricter content controls, though disabling hardware-accelerated graphics or WebGL only reduces some attack surface and will not fully close an integer-overflow path in the Graphics component, so patching remains the only reliable remedy.

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Technical ContextAI · show details

The vulnerability lives in Firefox's Graphics subsystem, which handles rendering of images, canvas, WebGL, and other visual primitives - code paths that routinely parse attacker-controlled dimensions and buffer sizes from web content. CWE-190 (Integer Overflow or Wraparound) indicates that an arithmetic operation on a size or offset value wraps past its type's maximum, producing an undersized allocation or an out-of-bounds index; the 'Buffer Overflow' tag suggests the overflowed integer subsequently drives an undersized heap allocation followed by an out-of-bounds write. The single CPE (cpe:2.3:a:mozilla:firefox) confirms the desktop Firefox application is the affected surface, consistent with Mozilla's practice of batching graphics memory-safety fixes across mainline and ESR trains.

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Severity by source

Sources disagree (Medium–Critical)
Vendor (mozilla) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 8.8 HIGH

Network-reachable via web content with low complexity and no auth, but the victim must load the malicious page, so UI:R rather than the input's UI:N; impact is high memory corruption within the unchanged content-process scope.

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 HIGH
Red Hat 6.1 MEDIUM

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
CVSS changed
Aug 19, 2026 - 13:22 NVD
9.8 (CRITICAL)
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)
CVE Published
Aug 18, 2026 - 12:23 cve.org
CRITICAL 9.8

DescriptionCVE.org

Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, and Firefox ESR 153.1.

Executive ViewAI

Why It Matters

A critical vulnerability in Mozilla Firefox (CVE-2026-74964) allows remote code execution when users visit compromised websites; no public exploit has been identified at time of analysis. Mozilla has released patches available in Firefox version 154 and later. All Firefox users across the organization face immediate risk of device compromise, making urgent patching a critical priority to prevent potential lateral network access and data exfiltration.

Business Impact: Severe
Compensating Controls

Vendor-released patch: Firefox 154 and patched ESR branches per MFSA2026-74 through MFSA2026-80 advisories.

Threat Intelligence Overview

EPSS Score
0.2%
Top 95% exploitable
Prevalence
High
one of the most widely deployed desktop web browsers worldwide
Data Quality
4 sources
Confidence: Medium
EUVD 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 CRITICAL
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
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
Out-of-Cycle
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Very High

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Integer Overflow MEDIUM

Integer overflow occurs when an arithmetic operation produces a result that exceeds the maximum value a given integer type can store.

Affected Products (CPE)CVE.org

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

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Same weakness CWE-190 – Integer Overflow or Wraparound

View all
CVE-2013-2729 CRITICAL POC
9.8
CVE-2015-8651 HIGH
8.8
CVE-2012-5054 HIGH POC
8.8
CVE-2014-0569 CRITICAL POC
9.3
CVE-2023-21716 CRITICAL POC
9.8
CVE-2017-3599 HIGH POC
7.5
CVE-2017-7529 HIGH
7.5
CVE-2016-1010 HIGH
8.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

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-2026-74964 ADVISORY https://vuldb.com/vuln/391616 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:3658/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=2053327 REF https://www.mozilla.org/security/advisories/mfsa2026-74/ 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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