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Mozilla CVE-2026-5735

| EUVDEUVD-2026-19616 CRITICAL
Out-of-bounds Write (CWE-787)
2026-04-07 mozilla
Memory Corruption Buffer Overflow Mozilla RCE
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
SUSE
8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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

6
Analysis Updated
Apr 16, 2026 - 05:45 EUVD-patch-fix
executive_summary
Re-analysis Queued
Apr 16, 2026 - 05:29 backfill_euvd_patch
patch_released
Patch available
Apr 16, 2026 - 05:29 EUVD
149.0.2
EUVD ID Assigned
Apr 07, 2026 - 13:00 euvd
EUVD-2026-19616
Analysis Generated
Apr 07, 2026 - 13:00 vuln.today
CVE Published
Apr 07, 2026 - 12:43 nvd
CRITICAL 9.8

DescriptionNVD

Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149.0.2.

AnalysisAI

Remote code execution in Mozilla Firefox versions prior to 149.0.2 stems from multiple memory safety bugs allowing unauthenticated network attackers to execute arbitrary code without user interaction. Mozilla confirmed memory corruption evidence across affected versions (Firefox 149.0.1 and Thunderbird 149.0.1), though Thunderbird patch status remains unconfirmed. CVSS 9.8 reflects maximum severity due to network-accessible attack vector with no complexity barriers. No public exploit identified at time of analysis, though the CWE-787 out-of-bounds write class has high weaponization potential once technical details emerge from linked Bugzilla entries.

Technical ContextAI

This vulnerability represents a collection of memory safety issues rooted in CWE-787 (Out-of-bounds Write), a memory corruption class enabling attackers to write data beyond allocated buffer boundaries. Firefox's multi-process architecture (Electrolysis) and complex rendering engine create extensive attack surface for memory corruption primitives. The CPE identifier cpe:2.3:a:mozilla:firefox confirms affected product scope. While the description mentions both Firefox and Thunderbird 149.0.1 as vulnerable, only Firefox appears in the official CPE data, suggesting shared codebase components (likely Gecko rendering engine) are affected. Out-of-bounds write vulnerabilities frequently serve as foundations for exploit chains targeting browser sandbox escapes, particularly when combined with additional information disclosure primitives to defeat ASLR and other exploit mitigations present in modern Firefox builds.

RemediationAI

Vendor-released patch: Mozilla Firefox 149.0.2 addresses all identified memory safety bugs per MFSA-2026-25. Users should immediately upgrade to Firefox 149.0.2 or later through Firefox's built-in update mechanism (Menu > Help > About Firefox triggers automatic update check) or download directly from mozilla.org. Enterprise deployments using Extended Support Release (ESR) channel should consult https://www.mozilla.org/security/advisories/mfsa2026-25/ for ESR-specific patch availability, as ESR versioning follows separate numbering scheme. For air-gapped or update-restricted environments where immediate patching is infeasible, network-layer controls restricting Firefox's attack surface (application firewalling, strict content security policies, JavaScript disabled for untrusted sites) provide partial risk reduction, though complete mitigation requires applying vendor patch. Organizations should verify Thunderbird patch status independently if using affected 149.0.1 version, as remediation guidance in provided data focuses exclusively on Firefox despite vulnerability description mentioning both products.

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Same weakness CWE-787 – Out-of-bounds Write

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CVE-2014-1761 HIGH POC
7.8
CVE-2009-3129 HIGH POC
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CVE-2021-1732 HIGH POC
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CVE-2013-3346 CRITICAL POC
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Same technique Memory Corruption

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CVE-2015-5119 CRITICAL POC
9.8
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9.8
CVE-2011-2462 CRITICAL POC
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CVE-2011-0611 HIGH POC
8.8
CVE-2014-0322 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8
CVE-2012-4792 HIGH POC
8.8
CVE-2010-3333 HIGH POC
7.8

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-2026-5735 vulnerability details – vuln.today
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