Mozilla Firefox up to 154 WebExtensions information disclosure

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.2$0-$5k0.00

Summaryinfo

A vulnerability described as problematic has been identified in Mozilla Firefox up to 154. The affected element is an unknown function of the component WebExtensions. Executing a manipulation can lead to information disclosure. This vulnerability is tracked as CVE-2026-84127. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in Mozilla Firefox up to 154. This vulnerability affects an unknown code block of the component WebExtensions. The manipulation with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. CVE summarizes:

Information disclosure in the WebExtensions component in Firefox for Android. This vulnerability was fixed in Firefox 155.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability was named CVE-2026-84127 since 09/01/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/08/2026). The MITRE ATT&CK project declares the attack technique as T1592.

The vulnerability scanner Nessus provides a plugin with the ID 342196 (Linux Distros Unpatched Vulnerability : CVE-2026-84127), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 155 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (342196) and CERT Bund (WID-SEC-2026-3132). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • SUSE openSUSE
  • 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: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 4.3
ADP CISA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
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: 342196
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-84127

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 155

Timelineinfo

09/01/2026 Advisory disclosed
09/01/2026 +0 days CVE reserved
09/01/2026 +0 days VulDB entry created
09/08/2026 +7 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-84127 (🔒)
GCVE (CVE): GCVE-0-2026-84127
GCVE (VulDB): GCVE-100-397612
CERT Bund: WID-SEC-2026-3132 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 09/01/2026 15:01
Updated: 09/08/2026 05:26
Changes: 09/01/2026 15:01 (57), 09/02/2026 20:52 (2), 09/07/2026 00:34 (10), 09/08/2026 05:26 (7)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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