Skip to main content

Firefox CVE-2026-84145

| EUVDEUVD-2026-69068 HIGH
Buffer Overflow (CWE-119)
2026-09-01 mozilla GHSA-6w89-9jrv-4j59
Buffer Overflow Red Hat Mozilla
7.5
CVSS 3.1 · Vendor: mozilla
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Attacker hosts malicious webpage
  2. Delivery
    Victim navigates to page in Firefox
  3. Exploit
    Crafted content triggers memory corruption (CWE-119)
  4. Execution
    Corrupt memory exploited for arbitrary code execution
  5. Impact
    Code executes within Firefox renderer process

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.

Sign in to read
Exploitation Conditions

User interaction is required - the victim must navigate to attacker-controlled web content (UI:R). High attack complexity (AC:H) means exploitation depends on specific memory layout conditions or race conditions within the browser engine, significantly reducing the reliability and ease of weaponization. No authentication or special browser configuration is required (PR:N); any user running an affected Firefox version on any platform is in scope for the attack surface. Exploitation is limited by: the AC:H complexity barrier (attacker must engineer a reliable memory corruption trigger), the S:U unchanged scope (full OS compromise requires a separate sandbox escape beyond browser RCE), and the requirement for user navigation to the malicious page. Default Firefox installations are in scope; no non-default configuration is required to be vulnerable.
Impact

CVSS 7.5 with AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H correctly captures the attack profile: network-reachable (browser), no credentials needed, but high complexity (AC:H) reflects that exploitation requires specific conditions to trigger the correct memory corruption path, and UI:R requires user navigation to attacker-controlled content. The unchanged scope (S:U) limits blast radius to the browser process, though Firefox's multi-process architecture means renderer compromise still requires a separate sandbox escape for full OS impact. No EPSS data is provided in the input, no KEV listing exists, and no public POC is available - this is no public exploit identified at time of analysis. Despite the impressive CVSS C:H/I:H/A:H triad, the AC:H and UI:R combination meaningfully raises the real-world exploitation bar. These are internally found bugs with no evidence of in-the-wild exploitation. Priority should reflect Firefox's ubiquitous deployment footprint and the ease of patching via browser auto-update rather than active threat intelligence.
Exploit ScenarioDerived

An attacker hosts a malicious webpage containing JavaScript or HTML content crafted to trigger a specific memory corruption condition in Firefox's rendering engine or SpiderMonkey JIT. When a targeted user visits the page, the corrupt memory state is manipulated to achieve arbitrary code execution within the Firefox renderer process. No public POC exists, but the AC:H requirement means an attacker would need prior research into the exact bug trigger conditions from the Bugzilla issue list.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.4% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Sep 01, 2026

Memory corruption vulnerabilities internally discovered across multiple Firefox release lines (154, ESR 153.1, ESR 140.14, ESR 115.39) could enable remote code execution when a user visits a specially crafted webpage. Mozilla's security team identified a cluster of memory safety bugs spanning 15+ tracked Bugzilla issues, several of which showed direct evidence of memory corruption sufficient to presume exploitability with sufficient attacker effort. Patches are available across all affected branches (Firefox 155, ESR 115.40, ESR 140.15, ESR 153.2); no public exploit code or CISA KEV listing is associated with this advisory.

RemediationAI

Upgrade to Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, or Firefox ESR 153.2, which contain the complete set of memory safety fixes. These releases are documented across Mozilla advisories MFSA2026-82 (https://www.mozilla.org/security/advisories/mfsa2026-82/), MFSA2026-83, MFSA2026-84, and MFSA2026-85. For end-user environments, enabling Firefox's built-in auto-update is the primary control with no meaningful side effects. For enterprise deployments on ESR 115.x (common in managed environments), coordinated update deployment via MDM or policy tools should be prioritized given the high CVSS impact. If patching is temporarily delayed, restricting access to untrusted web content (web filtering, application allowlisting) reduces the user-interaction attack vector. No functional workaround exists within Firefox itself that eliminates the underlying memory safety risk.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Sign in to check
Technical ContextAI · show details

CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) encompasses the root-cause class here: browser engine memory safety errors including out-of-bounds reads/writes and heap corruption. Firefox's layout engine, JavaScript runtime (SpiderMonkey), and media subsystems are historically the most common sources of such bugs. The CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* confirms the vulnerability class spans the upstream Firefox codebase itself, not a platform-specific component. Multiple Bugzilla bug IDs across two distinct groupings (15 bugs in one list, 4 in another, plus a singleton) indicate this is a catch-all memory safety advisory rather than a single discrete vulnerability, which is consistent with Mozilla's MFSA practice for internally found bug batches.

Know when Mozilla gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources
Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

Vendor (mozilla) PRIMARY 7.5 HIGH
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
vuln.today AI 7.5 HIGH

Network vector with user interaction aligns with browser exploitation; AC:H reflects multiple complex memory corruption triggers with no guaranteed reliable primitive.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

3
CVSS changed
Sep 01, 2026 - 15:22 NVD
7.5 (HIGH)
CVE Published
Sep 01, 2026 - 12:18 cve.org
UNKNOWN (no severity yet)
CVE Published
Sep 01, 2026 - 12:18 cve.org
HIGH 7.5

DescriptionCVE.org

Internally found bugs present in Firefox 154, Firefox ESR 153.1, Firefox ESR 140.14 and Firefox ESR 115.39. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2.

Articles & Coverage 1

News 7 New Mozilla Vulnerabilities - 2 Critical, 5 High Severity Sep 02, 2026

Executive ViewAI

Why It Matters

Mozilla Firefox versions 154, ESR 153.1, ESR 140.14, and ESR 115.39 contain memory corruption vulnerabilities enabling remote code execution when users visit malicious webpages. Organizations with deployed Firefox installations face direct risk of system compromise through user browsing activity; immediate patching to vendor-released versions is required to prevent potential code execution attacks.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
0.4%
Top 67% exploitable
Prevalence
Ubiquitous
major global browser, hundreds of millions of active installs
Data Quality
7 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS Vulnrichment 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 0.4%
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
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.

Affected Products (CPE)CVE.org

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

More in Mozilla

View all
CVE-2015-4495 HIGH POC
8.8 Aug 08

The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote
CVE-2013-1690 HIGH POC
8.8 Jun 26

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before

CVE-2013-0758 CRITICAL POC
9.3 Jan 13

Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderb
CVE-2013-0753 CRITICAL POC
9.3 Jan 13

Use-after-free vulnerability in the serializeToStream implementation in the XMLSerializer component in Mozilla Firefox b
CVE-2012-3993 CRITICAL POC
9.3 Oct 10

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbi
CVE-2013-1710 CRITICAL POC
10.0 Aug 07

The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo
CVE-2017-3823 HIGH POC
8.8 Feb 01

An issue was discovered in the Cisco WebEx Extension before 1.0.7 on Google Chrome, the ActiveTouch General Plugin Conta
CVE-2014-8636 HIGH POC
7.5 Jan 14

The XrayWrapper implementation in Mozilla Firefox before 35.0 and SeaMonkey before 2.32 does not properly interact with

CVE-2013-0757 CRITICAL POC
9.3 Jan 13

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
9.8 Mar 19

Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25 allow remo
CVE-2013-0643 HIGH
8.8 Feb 27

The Firefox sandbox in Adobe Flash Player before 10.3.183.67 and 11.x before 11.6.602.171 on Windows and Mac OS X, and b

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
7.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Important
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-84145 ADVISORY https://vuldb.com/vuln/397618 REF https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054640%2C2054650%2C2054652%2C2055693%2C2055705%2C2058051%2C2058652%2C2058660%2C2059027%2C2061220%2C2061242%2C2061285%2C2061300%2C2061316%2C2061397 REF https://bugzilla.mozilla.org/buglist.cgi?bug_id=2058001%2C2059139%2C2062400%2C2062419 REF https://bugzilla.mozilla.org/show_bug.cgi?id=2055678 REF https://www.mozilla.org/security/advisories/mfsa2026-82/ REF https://www.mozilla.org/security/advisories/mfsa2026-83/ REF https://www.mozilla.org/security/advisories/mfsa2026-84/ REF https://www.mozilla.org/security/advisories/mfsa2026-85/ REF https://www.mozilla.org/security/advisories/mfsa2026-86/ REF https://www.mozilla.org/security/advisories/mfsa2026-87/ REF https://www.mozilla.org/security/advisories/mfsa2026-88/

Search Externally

GitHub PoC Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy