Mozilla Firefox up to 153.1/154 Navigation isolation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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8.5$5k-$25k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 153.1/154. Affected by this issue is some unknown functionality of the component Navigation Component. Performing a manipulation results in isolation. This vulnerability is cataloged as CVE-2026-84140. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Mozilla Firefox up to 153.1/154. This affects an unknown functionality of the component Navigation Component. The manipulation with an unknown input leads to a isolation vulnerability. CWE is classifying the issue as CWE-653. The product does not properly compartmentalize or isolate functionality, processes, or resources that require different privilege levels, rights, or permissions. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2026-84140 since 09/01/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 09/23/2026).

The vulnerability scanner Nessus provides a plugin with the ID 342307 (Linux Distros Unpatched Vulnerability : CVE-2026-84140), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 153.2 or 155 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (342307) and CERT Bund (WID-SEC-2026-3132). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Debian Linux
  • Red Hat Enterprise Linux
  • IGEL OS
  • SUSE Linux
  • SUSE openSUSE
  • Oracle Linux
  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.6
VulDB Meta Temp Score: 8.5

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

ADP CISA Base Score: 9.8
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Isolation
CWE: CWE-653
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 342307
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-84140

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 153.2/155

Timelineinfo

09/01/2026 Advisory disclosed
09/01/2026 +0 days CVE reserved
09/01/2026 +0 days VulDB entry created
09/23/2026 +22 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-84140 (🔒)
GCVE (CVE): GCVE-0-2026-84140
GCVE (VulDB): GCVE-100-397629
CERT Bund: WID-SEC-2026-3132 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 09/01/2026 15:16
Updated: 09/23/2026 09:34
Changes: 09/01/2026 15:16 (57), 09/03/2026 01:49 (2), 09/07/2026 06:44 (21), 09/08/2026 10:41 (7), 09/23/2026 09:34 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion

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