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Firefox CVE-2026-6758

| EUVDEUVD-2026-24099 HIGH
Use After Free (CWE-416)
2026-04-21 mozilla GHSA-28xp-3gpw-3vvp
Information Disclosure Memory Corruption Use After Free Mozilla Red Hat Suse
7.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative
Red Hat
6.1 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

8
Patch released
Apr 29, 2026 - 02:30 nvd
Patch available
Analysis Updated
Apr 22, 2026 - 00:38 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Apr 22, 2026 - 00:22 vuln.today
cvss_changed
Analysis Generated
Apr 21, 2026 - 18:23 vuln.today
CVSS changed
Apr 21, 2026 - 18:22 NVD
7.5 (HIGH)
EUVD ID Assigned
Apr 21, 2026 - 13:15 euvd
EUVD-2026-24099
Analysis Generated
Apr 21, 2026 - 13:15 vuln.today
CVE Published
Apr 21, 2026 - 12:40 nvd
HIGH 7.5

DescriptionCVE.org

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.

AnalysisAI

Use-after-free in Firefox's WebAssembly JavaScript engine enables remote denial-of-service attacks against users running unpatched versions below Firefox 150. The vulnerability allows network-based attackers to crash the browser without authentication or user interaction by triggering memory corruption in WebAssembly processing. Mozilla patched this in Firefox 150 (MFSA2026-30). EPSS data not available, not listed in CISA KEV, and SSVC framework rates exploitation as 'none' with non-automatable, partial technical impact-suggesting lower real-world risk despite CVSS 7.5 severity.

Technical ContextAI

This is a use-after-free (CWE-416) vulnerability in Firefox's WebAssembly runtime component, which executes low-level bytecode within the JavaScript engine. Use-after-free occurs when memory is accessed after being deallocated, leading to memory corruption that attackers can trigger to cause crashes or potentially control program execution. WebAssembly is a binary instruction format for stack-based virtual machines, enabling near-native performance for web applications. The affected component is specifically the JavaScript integration layer with WebAssembly (identified by Mozilla as JavaScript: WebAssembly). According to CPE data, all Firefox versions prior to the fix are affected: cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*. The CVSS vector indicates network-based exploitation with low attack complexity and no special requirements, but impact is limited to availability (high availability impact, no confidentiality or integrity impact).

RemediationAI

Upgrade to Firefox 150 or later, as confirmed by Mozilla Security Advisory MFSA2026-30 (https://www.mozilla.org/security/advisories/mfsa2026-30/). Firefox typically auto-updates within 24-48 hours of release; verify current version by navigating to Firefox menu > Help > About Firefox. For enterprise deployments with managed updates, prioritize deployment within standard patch cycles given the denial-of-service-only impact and lack of observed exploitation. If immediate patching is not feasible, temporary compensating controls include disabling WebAssembly via browser configuration (set javascript.options.wasm to false in about:config), though this will break WebAssembly-dependent web applications including some games, CAD tools, and video editors-assess application compatibility before deployment. Network-level controls are ineffective since this is a client-side browser vulnerability triggered by content. For high-security environments where WebAssembly is not required, consider organizational policy to disable it permanently, accepting application compatibility trade-offs in exchange for reduced attack surface.

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Same weakness CWE-416 – Use After Free

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Same technique Information Disclosure

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Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Fixed

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CVE-2026-6758 vulnerability details – vuln.today
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