Mozilla Firefox up to 85.x on Android Fullscreen ui layer

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 85.x on Android. This impacts an unknown function of the component Fullscreen Handler. The manipulation leads to ui layer. This vulnerability is referenced as CVE-2021-23976. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 85.x on Android (Web Browser) and classified as critical. This issue affects an unknown functionality of the component Fullscreen Handler. The manipulation with an unknown input leads to a ui layer vulnerability. Using CWE to declare the problem leads to CWE-1021. The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with. Impacted is confidentiality, integrity, and availability.

The weakness was published 02/26/2021. The advisory is shared at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2021-23976. 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 $0-$5k at the moment (estimation calculated on 08/12/2025).

The vulnerability scanner Nessus provides a plugin with the ID 247761 (Linux Distros Unpatched Vulnerability : CVE-2021-23976), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 86.0 eliminates this vulnerability. The upgrade is hosted for download at mozilla.org.

The vulnerability is also documented in the vulnerability database at Tenable (247761). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.2
VulDB Meta Temp Score: 7.0

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

NVD Base Score: 8.1
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Ui layer
CWE: CWE-1021
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: 247761
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-23976

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Firefox 86.0

Timelineinfo

01/13/2021 🔍
02/26/2021 +44 days 🔍
02/26/2021 +0 days 🔍
08/12/2025 +1628 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2021-23976 (🔍)
GCVE (CVE): GCVE-0-2021-23976
GCVE (VulDB): GCVE-100-170465
scip Labs: https://www.scip.ch/en/?labs.20130704

Entryinfo

Created: 02/26/2021 10:09
Updated: 08/12/2025 02:42
Changes: 02/26/2021 10:09 (43), 03/05/2021 15:16 (5), 03/05/2021 15:18 (18), 08/12/2025 02:42 (17)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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