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Mozilla Firefox CVE-2026-74943

| EUVDEUVD-2026-60750 CRITICAL
Use After Free (CWE-416)
2026-08-18 mozilla GHSA-cx5v-35ww-82cj
Use After Free Information Disclosure Mozilla Memory Corruption Red Hat Suse
9.8
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.5 HIGH

Remote via crafted image but requires the victim to load content (UI:R) and reliable UAF exploitation needs heap grooming/sandbox defeat (AC:H); full C/I/A impact within the content process.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
Analysis Generated
Aug 20, 2026 - 23:09 vuln.today
CVSS changed
Aug 20, 2026 - 20:37 NVD
9.8 (CRITICAL)
CVE Published
Aug 18, 2026 - 12:23 nvd
CRITICAL 9.8
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionNVD

Use-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, and Firefox ESR 153.1.

AnalysisAI

Memory corruption via a use-after-free in Firefox's Graphics: ImageLib component allows a remote attacker to potentially execute code or disclose memory contents when a victim renders attacker-controlled image data. All Firefox channels are affected up to the fixed builds (Firefox 154 and ESR 115.39, 140.14, 153.1). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Host crafted image on web page
Delivery
Lure victim to load page
Exploit
Firefox ImageLib decodes malformed image
Execution
Trigger use-after-free on freed surface
Persist
Groom heap for controlled reuse
Impact
Leak memory or execute code in content process
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Vulnerability AssessmentAI

Exploitation Exploitation requires the victim's Firefox to decode attacker-supplied image data through the ImageLib component - i.e., the user must visit a malicious or compromised page, open an HTML email that auto-loads images, or otherwise load the crafted image; this user-interaction requirement is the primary limiting factor and contradicts the published UI:N metric. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The signals conflict and should be read carefully. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker hosts a web page embedding a specially crafted image, or injects such an image into a site or ad network the victim visits. When Firefox's ImageLib decodes the malformed image it triggers the use-after-free, letting the attacker leak adjacent heap memory or, chained with heap grooming, corrupt memory toward code execution in the content process. …
Remediation Vendor-released patch: upgrade to Firefox 154, or to Firefox ESR 115.39, ESR 140.14, or ESR 153.1 depending on your deployed ESR line, per Mozilla advisories mfsa2026-74 through mfsa2026-80 (https://www.mozilla.org/security/advisories/mfsa2026-74/). … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: Audit Firefox deployments to determine installed versions and user count; implement browser policies restricting image loading from untrusted sources where operationally feasible. …

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Same weakness CWE-416 – Use After Free

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Same technique Use After Free

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8.1

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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CVE-2026-74943 vulnerability details – vuln.today
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