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Mozilla CVE-2025-6436

| EUVDEUVD-2025-19098 HIGH
Buffer Overflow (CWE-119)
2025-06-24 security@mozilla.org
RCE Mozilla Buffer Overflow
8.1
CVSS 3.1 · NVD
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Severity by source

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

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

4
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
EUVD ID Assigned
Mar 15, 2026 - 22:36 euvd
EUVD-2025-19098
Analysis Generated
Mar 15, 2026 - 22:36 vuln.today
CVE Published
Jun 24, 2025 - 13:15 nvd
HIGH 8.1

DescriptionCVE.org

Memory safety bugs present in Firefox 139 and Thunderbird 139. 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 < 140 and Thunderbird < 140.

AnalysisAI

CVE-2025-6436 is a collection of memory safety vulnerabilities in Firefox and Thunderbird versions 139 that demonstrate evidence of memory corruption with potential for arbitrary code execution. The vulnerability affects Firefox < 140 and Thunderbird < 140, and requires network access but moderate attack complexity. While no active exploitation in the wild has been confirmed, the high CVSS score of 8.1 and memory corruption evidence indicate this is a critical patch requiring immediate deployment.

Technical ContextAI

This vulnerability stems from CWE-119 (Buffer Errors), a memory safety class affecting unsafe memory operations in C/C++ codebases. Firefox and Thunderbird are built on the Gecko rendering engine, which handles complex parsing of web content, HTML, JavaScript, and email attachments. The 'memory safety bugs' classification indicates multiple distinct buffer overflow, out-of-bounds access, or use-after-free conditions were discovered during version 139 development. The root cause reflects the inherent challenges in memory management within large-scale browser engines processing untrusted input from diverse sources (web pages, email, plugins). These bugs were identified and patched before version 140 release.

RemediationAI

Immediate action: Update Firefox to version 140 or later and Thunderbird to version 140 or later. Users should enable automatic updates if not already configured (default for most installations). Mozilla's security advisory for this CVE (referenced in the description) provides specific version information. No workarounds mitigate memory corruption vulnerabilities; patching is mandatory. Organizations should prioritize deployment of Firefox 140+ and Thunderbird 140+ patches across all systems. Verify patch deployment through version checking in about:firefox and about:support dialogs. For enterprise environments, consider mandatory update policies via GPO (Windows) or MDM solutions.

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Same weakness CWE-119 – Buffer Overflow

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8.8
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Same technique RCE

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Vendor StatusVendor

Ubuntu

Priority: Medium
firefox
Release Status Version
jammy not-affected code not present
noble not-affected code not present
oracular not-affected code not present
plucky not-affected code not present
upstream needs-triage -
questing not-affected code not present
thunderbird
Release Status Version
noble not-affected code not present
oracular not-affected code not present
plucky not-affected code not present
upstream released 140
questing not-affected code not present
jammy released 1:140.7.1+build1-0ubuntu0.22.04.1
mozjs38
Release Status Version
bionic needs-triage -
jammy DNE -
noble DNE -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs52
Release Status Version
bionic ignored -
focal ignored -
jammy DNE -
noble DNE -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs68
Release Status Version
focal ignored -
jammy DNE -
noble DNE -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs78
Release Status Version
jammy ignored -
noble DNE -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs91
Release Status Version
jammy ignored -
noble DNE -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs102
Release Status Version
jammy ignored -
noble ignored -
oracular DNE -
plucky DNE -
upstream needs-triage -
questing DNE -
mozjs115
Release Status Version
jammy DNE -
noble ignored -
oracular ignored -
plucky ignored -
upstream needs-triage -
questing DNE -
USN-7991-1

Debian

firefox
Release Status Fixed Version Urgency
sid fixed 148.0.2-1 -
(unstable) fixed 140.0-1 -

SUSE

Severity: High
Product Status
Image SLES12-SP5-SAP-Azure-LI-BYOS-Production Image SLES12-SP5-SAP-Azure-VLI-BYOS-Production Affected
Image SLES15-SP4-SAP-Azure-LI-BYOS Image SLES15-SP4-SAP-Azure-LI-BYOS-Production Image SLES15-SP4-SAP-Azure-VLI-BYOS Image SLES15-SP4-SAP-Azure-VLI-BYOS-Production Affected
Image SLES15-SP5-SAP-Azure-LI-BYOS Image SLES15-SP5-SAP-Azure-LI-BYOS-Production Image SLES15-SP5-SAP-Azure-VLI-BYOS Image SLES15-SP5-SAP-Azure-VLI-BYOS-Production Affected
Image SLES15-SP6-SAP-Azure-LI-BYOS Image SLES15-SP6-SAP-Azure-LI-BYOS-Production Image SLES15-SP6-SAP-Azure-VLI-BYOS Image SLES15-SP6-SAP-Azure-VLI-BYOS-Production Image SLES15-SP7-SAP-Azure-LI-BYOS-Production Image SLES15-SP7-SAP-Azure-VLI-BYOS-Production Affected
SUSE Enterprise Storage 7.1 Fixed

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CVE-2025-6436 vulnerability details – vuln.today
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