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7.5
HIGH CVSS 3.1
CVE-2026-84144
Internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
Overview
Description

Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. 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 153.2, Thunderbird 155, and Thunderbird 153.2.

Details
INFO

Published Date :

Sept. 1, 2026, 1:20 p.m.

Last Modified :

Sept. 3, 2026, 4:33 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-84144 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Mozilla firefox
2 Mozilla thunderbird
: Total Affected Vendor : 1 | Products : 2
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH 134c704f-9b21-4f2e-91b3-4a467353bcc0
Solution
Update Firefox to version 155 or Firefox ESR to 153.2 to fix memory corruption vulnerabilities.
  • Update Firefox to version 155.
  • Update Firefox ESR to version 153.2.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-84144.

URL Resource
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054619%2C2054620%2C2054624%2C2054702%2C2054726%2C2054775%2C2055703%2C2058006%2C2058013%2C2058098%2C2058627%2C2058661%2C2059127%2C2059128%2C2059180%2C2059199%2C2059205%2C2061320%2C2061430%2C2061495%2C2061505%2C2061532%2C2061799 Broken Link
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054625%2C2059002%2C2061775 Broken Link
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054691%2C2058085%2C2059144%2C2059191%2C2059192%2C2061521%2C2062395%2C2062404 Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-82/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-85/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-86/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-88/ Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-84144 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-84144 weaknesses.

CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-42: MIME Conversion MIME Conversion CAPEC-44: Overflow Binary Resource File Overflow Binary Resource File CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-100: Overflow Buffers Overflow Buffers CAPEC-123: Buffer Manipulation Buffer Manipulation

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-84144 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-84144 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Sep. 03, 2026

    Action Type Old Value New Value
    Added CPE Configuration OR *cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* versions up to (excluding) 153.2.0 *cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* versions from (including) 154.0.0 up to (excluding) 155.0.0 *cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* versions up to (excluding) 153.2.0 *cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* versions from (including) 154.0 up to (excluding) 155.0
    Added Reference Type Mozilla Corporation: https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054619%2C2054620%2C2054624%2C2054702%2C2054726%2C2054775%2C2055703%2C2058006%2C2058013%2C2058098%2C2058627%2C2058661%2C2059127%2C2059128%2C2059180%2C2059199%2C2059205%2C2061320%2C2061430%2C2061495%2C2061505%2C2061532%2C2061799 Types: Broken Link
    Added Reference Type Mozilla Corporation: https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054625%2C2059002%2C2061775 Types: Broken Link
    Added Reference Type Mozilla Corporation: https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054691%2C2058085%2C2059144%2C2059191%2C2059192%2C2061521%2C2062395%2C2062404 Types: Broken Link
    Added Reference Type Mozilla Corporation: https://www.mozilla.org/security/advisories/mfsa2026-82/ Types: Vendor Advisory
    Added Reference Type Mozilla Corporation: https://www.mozilla.org/security/advisories/mfsa2026-85/ Types: Vendor Advisory
    Added Reference Type Mozilla Corporation: https://www.mozilla.org/security/advisories/mfsa2026-86/ Types: Vendor Advisory
    Added Reference Type Mozilla Corporation: https://www.mozilla.org/security/advisories/mfsa2026-88/ Types: Vendor Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 03, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
    Added CWE CWE-119
    Added SSVC {'id': 'CVE-2026-84144', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-03T15:41:23.728845Z'}
  • CVE Modified by [email protected]

    Sep. 01, 2026

    Action Type Old Value New Value
    Changed Description Internally found bugs present in Firefox 154 and Firefox ESR 153.1. 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 and Firefox ESR 153.2. Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. 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 153.2, Thunderbird 155, and Thunderbird 153.2.
    Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/84xxx/CVE-2026-84144.json">CVE-2026-84144</a>
    Added Reference https://www.mozilla.org/security/advisories/mfsa2026-86/
    Added Reference https://www.mozilla.org/security/advisories/mfsa2026-88/
  • New CVE Received by [email protected]

    Sep. 01, 2026

    Action Type Old Value New Value
    Added Description Internally found bugs present in Firefox 154 and Firefox ESR 153.1. 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 and Firefox ESR 153.2.
    Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/84xxx/CVE-2026-84144.json">CVE-2026-84144</a>
    Added Reference https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054619%2C2054620%2C2054624%2C2054702%2C2054726%2C2054775%2C2055703%2C2058006%2C2058013%2C2058098%2C2058627%2C2058661%2C2059127%2C2059128%2C2059180%2C2059199%2C2059205%2C2061320%2C2061430%2C2061495%2C2061505%2C2061532%2C2061799
    Added Reference https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054625%2C2059002%2C2061775
    Added Reference https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054691%2C2058085%2C2059144%2C2059191%2C2059192%2C2061521%2C2062395%2C2062404
    Added Reference https://www.mozilla.org/security/advisories/mfsa2026-82/
    Added Reference https://www.mozilla.org/security/advisories/mfsa2026-85/
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 7.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact