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Mozilla Firefox CVE-2026-8391

| EUVDEUVD-2026-29466 MEDIUM
Improper Input Validation (CWE-20)
2026-05-12 mozilla GHSA-93pv-vhrf-wv64
Mozilla Information Disclosure
5.3
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
SUSE
MEDIUM
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:L/I:N/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

Lifecycle Timeline

4
Analysis Generated
May 13, 2026 - 16:23 vuln.today
CVSS changed
May 13, 2026 - 16:22 NVD
5.3 (MEDIUM)
CVE Published
May 12, 2026 - 12:36 nvd
UNKNOWN (no severity yet)
CVE Published
May 12, 2026 - 12:36 nvd
MEDIUM 5.3

DescriptionCVE.org

Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3.

AnalysisAI

Information disclosure vulnerability in Firefox's JavaScript Engine allows remote unauthenticated attackers to leak sensitive memory contents over the network without user interaction. The vulnerability affects Firefox versions prior to 150.0.3 and has a low EPSS score (0.02%) despite the network-based attack vector, suggesting limited real-world exploitation pressure despite the modest CVSS score of 5.3.

Technical ContextAI

The vulnerability resides in Firefox's JavaScript Engine component and is classified as CWE-20 (Improper Input Validation). The JavaScript Engine is the core runtime that interprets and executes JavaScript code in the browser. CWE-20 indicates that the engine fails to properly validate or sanitize input data, potentially allowing an attacker to craft malicious JavaScript that causes memory disclosure. The affected product is Mozilla Firefox across all versions up to and including 150.0.2, as indicated by the CPE string cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* with the vulnerability fixed in version 150.0.3.

RemediationAI

Vendor-released patch: Firefox 150.0.3 or later. Users should immediately update Firefox through the browser's built-in update mechanism (Help → About Firefox on most platforms) or download the latest version from mozilla.org. Firefox typically applies security updates automatically after download; restart the browser to complete patching. No workarounds are available for this JavaScript Engine vulnerability, as disabling JavaScript would eliminate browser functionality. Network-level controls (WAF rules, DNS filtering) are ineffective against browser-based memory disclosure, making patching the only viable mitigation.

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SUSE Linux Enterprise Server 12 SP5-LTSS Fixed
SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 Fixed
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected

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CVE-2026-8391 vulnerability details – vuln.today
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