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Mozilla Firefox CVE-2026-6749

| EUVDEUVD-2026-24090 HIGH
Use of Uninitialized Resource (CWE-908)
2026-04-21 mozilla GHSA-7gp8-9grp-c69x
Information Disclosure Mozilla
7.5
CVSS 3.1 · Vendor: mozilla
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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
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

9
Patch released
Apr 29, 2026 - 02:30 nvd
Patch available
Analysis Updated
Apr 22, 2026 - 00:43 vuln.today
v3 (cvss_changed)
Analysis Updated
Apr 22, 2026 - 00:42 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Apr 22, 2026 - 00:22 vuln.today
cvss_changed
Analysis Generated
Apr 21, 2026 - 18:22 vuln.today
CVSS changed
Apr 21, 2026 - 18:22 NVD
7.5 (HIGH)
EUVD ID Assigned
Apr 21, 2026 - 13:15 euvd
EUVD-2026-24090
Analysis Generated
Apr 21, 2026 - 13:15 vuln.today
CVE Published
Apr 21, 2026 - 12:40 nvd
HIGH 7.5

DescriptionCVE.org

Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, and Firefox ESR 140.10.

AnalysisAI

Uninitialized memory in Firefox's Canvas2D graphics component allows remote attackers to disclose sensitive information from browser memory without authentication. Affects Firefox versions prior to 150, ESR prior to 115.35, and ESR prior to 140.10. The vulnerability carries a CVSS score of 7.5 with network-based exploitation requiring low complexity and no user interaction. SSVC framework indicates no confirmed exploitation and non-automatable attack, but EPSS data not available to assess real-world exploitation probability. Mozilla has released patches across all affected product lines.

Technical ContextAI

This vulnerability (CWE-908: Use of Uninitialized Resource) affects the Canvas2D rendering engine within Firefox's graphics subsystem. Canvas2D is a web standard API that allows JavaScript to draw 2D graphics and images within HTML5 canvas elements. When memory is allocated for canvas operations but not properly initialized before use, residual data from previous operations or other browser processes can remain in that memory space. An attacker can craft malicious JavaScript that triggers canvas operations in a way that causes this uninitialized memory to be read and returned to the web page context, potentially exposing sensitive information such as previously rendered content, user data, or internal browser state. The CPE identifier cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* confirms this affects the Mozilla Firefox application across multiple version branches including the standard release channel and Extended Support Release (ESR) channels.

RemediationAI

Upgrade to Firefox 150 or later for standard release channel users, Firefox ESR 115.35 or later for ESR 115 branch users, or Firefox ESR 140.10 or later for ESR 140 branch users. Download patches from Mozilla's official security advisories at https://www.mozilla.org/security/advisories/mfsa2026-30/, mfsa2026-31/, mfsa2026-32/, mfsa2026-33/, or mfsa2026-34/. For environments unable to immediately patch, compensating controls include restricting browser access to untrusted websites through web filtering policies, deploying endpoint detection to monitor for suspicious canvas API usage patterns (though this may generate false positives from legitimate web applications), or temporarily disabling JavaScript for high-risk user populations (which will break significant web functionality and impact productivity). Network-level controls are ineffective as the attack vector is delivered through normal HTTPS web traffic. Organizations should prioritize patching over compensating controls given the availability of vendor fixes and the difficulty of reliably blocking canvas-based attacks without breaking legitimate web applications.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Liberty Linux 10 Fixed
SUSE Liberty Linux 8 Fixed
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Server 16.0 SUSE Linux Enterprise Server for SAP applications 16.0 Fixed
openSUSE Leap 16.0 Fixed

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CVE-2026-6749 vulnerability details – vuln.today
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