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Thunderbird CVE-2025-8034

HIGH
Buffer Overflow (CWE-119)
2025-07-22 security@mozilla.org
RCE Buffer Overflow Mozilla Thunderbird
8.8
CVSS 3.1 · Vendor: mozilla
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Vulnerability Assessment

Weakness
CWE
CWE-119
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 13, 2026

Remote code execution in Mozilla Firefox (ESR 115.x through 115.25, 128.x through 128.12, 140.0, regular 140) and Thunderbird (ESR 128.12, 140.0, regular 140) via memory safety bugs (CWE-119 buffer overflow). Attackers can execute arbitrary code by delivering crafted web content that triggers memory corruption when a user interacts with malicious pages or emails. CVSS 8.8 (High) reflects network-based attack requiring user interaction but no authentication. Vendor-released patches available: Firefox 141, Firefox ESR 115.26/128.13/140.1, Thunderbird 141/128.13/140.1. EPSS data not provided; no public exploit identified at time of analysis, though Mozilla notes evidence of memory corruption suggesting exploitability with effort.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (mozilla) PRIMARY 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Memory safety bugs present in Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird ESR 128.12, Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. 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 was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

Executive ViewAI

Why It Matters

Mozilla Firefox and Thunderbird versions 140.0 and earlier contain a critical memory safety vulnerability (CVE-2025-8034, CVSS 8.8) enabling remote code execution when users visit malicious websites or open crafted emails, affecting all employees using these applications across the organization. Immediate patching is required to prevent potential compromise of user systems and sensitive data exposure.

Recommended Action

Within 24 hours: Inventory all Firefox and Thunderbird deployments; identify affected versions (Firefox <141, Firefox ESR <115.26/128.13/140.1; Thunderbird <141/128.13/140.1). Within 7 days: Deploy Firefox 141 and Thunderbird 141 (or applicable ESR versions 115.26, 128.13, 140.1) across all endpoints via patch management system; validate successful updates on 100% of systems. Within 30 days: Conduct post-patch audit to confirm no systems remain on vulnerable versions; document remediation completion.

Business Impact: High
Compensating Controls

Apply vendor patch. Interim mitigations if patching is delayed: disable JavaScript in Firefox/Thunderbird email settings where operationally feasible; block known malicious domains at network perimeter; restrict user access to untrusted external websites; advise users to avoid clicking links in unsolicited emails until patches are applied.

Threat Intelligence Overview

EPSS Score
0.1%
Top 69% exploitable
Data Quality
5 sources
Confidence: Medium
NVD CVE.org EPSS Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
High

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

Affected Products (CPE)CVE.org

cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*

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The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo
CVE-2013-0757 CRITICAL POC
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The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbi
CVE-2014-1510 CRITICAL POC
9.8 Mar 19

The Web IDL implementation in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and Se
CVE-2014-1511 CRITICAL POC
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Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox

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Alpine Linux: mozjs fixed in 128.3.1-r0
CVE-2015-0816 MEDIUM POC
5.0 Apr 01

Mozilla Firefox before 37.0, Firefox ESR 31.x before 31.6, and Thunderbird before 31.6 do not properly restrict resource
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The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for

Same weakness CWE-119 – Buffer Overflow

View all
CVE-2020-0796 CRITICAL POC
10.0
CVE-2017-11882 HIGH POC
7.8
CVE-2014-6332 HIGH POC
8.8
CVE-2015-2426 HIGH POC
8.8
CVE-2013-3918 HIGH POC
8.8
CVE-2023-4966 HIGH POC
7.5
CVE-2017-11774 HIGH POC
7.8
CVE-2013-3660 HIGH POC
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Same technique RCE

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CVE-2021-44228 CRITICAL POC
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CVE-2017-7269 CRITICAL POC
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CVE-2022-47966 CRITICAL POC
9.8
CVE-2012-4681 CRITICAL POC
9.8
CVE-2023-3519 CRITICAL POC
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CVE-2015-5119 CRITICAL POC
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CVE-2016-4117 CRITICAL POC
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CVE-2015-3113 CRITICAL POC
9.8

Vendor StatusVendor

SUSE

Severity: High
Product Status
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-4.11 Affected
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

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2025:11747 ADVISORY https://access.redhat.com/errata/RHSA-2025:11748 ADVISORY https://access.redhat.com/errata/RHSA-2025:11797 ADVISORY https://access.redhat.com/errata/RHSA-2025:12044 ADVISORY https://access.redhat.com/errata/RHSA-2025:12045 ADVISORY https://access.redhat.com/errata/RHSA-2025:12046 ADVISORY https://access.redhat.com/errata/RHSA-2025:12187 ADVISORY https://access.redhat.com/errata/RHSA-2025:12188 ADVISORY https://access.redhat.com/errata/RHSA-2025:12278 ADVISORY https://access.redhat.com/errata/RHSA-2025:12302 ADVISORY https://access.redhat.com/errata/RHSA-2025:12353 ADVISORY https://access.redhat.com/errata/RHSA-2025:12360 ADVISORY https://access.redhat.com/errata/RHSA-2025:12361 ADVISORY https://access.redhat.com/errata/RHSA-2025:13645 ADVISORY https://access.redhat.com/errata/RHSA-2025:13646 ADVISORY https://access.redhat.com/errata/RHSA-2025:13647 ADVISORY https://access.redhat.com/errata/RHSA-2025:13648 ADVISORY https://access.redhat.com/errata/RHSA-2025:13649 ADVISORY https://access.redhat.com/errata/RHSA-2025:13650 ADVISORY https://access.redhat.com/errata/RHSA-2025:13651 ADVISORY https://access.redhat.com/errata/RHSA-2025:13676 ADVISORY https://vuldb.com/vuln/317336 ADVISORY https://vuldb.com/vuln/317337 ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-56/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-57/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-58/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-59/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-61/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-62/ ADVISORY https://www.mozilla.org/security/advisories/mfsa2025-63/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:02529/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:02531/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:02546/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21170/ REF https://bugzilla.mozilla.org/show_bug.cgi?id=1970422 REF https://lists.debian.org/debian-lts-announce/2025/07/msg00016.html

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