VDB-177563 · CVE-2021-23999 · Nessus 246702

Mozilla Firefox/Firefox ESR/Thunderbird Web Contents Remote Code Execution

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	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.
4.8	$0-$5k	0.00

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Mozilla Firefox, Firefox ESR and Thunderbird. Affected by this issue is some unknown functionality of the component Web Contents Handler. The manipulation leads to an unknown weakness. This vulnerability is listed as CVE-2021-23999. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Mozilla Firefox, Firefox ESR and Thunderbird (Web Browser) (affected version unknown). This issue affects an unknown functionality of the component Web Contents Handler. Impacted is confidentiality, integrity, and availability.

The weakness was presented 06/25/2021. It is possible to read the advisory at mozilla.org. The identification of this vulnerability is CVE-2021-23999. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 246702 (Linux Distros Unpatched Vulnerability : CVE-2021-23999), which helps to determine the existence of the flaw in a target environment.

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

The vulnerability is also documented in the vulnerability database at Tenable (246702). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Web Browser

Vendor

Mozilla

Name

License

open-source

Website

Vendor: https://www.mozilla.org/
Product: https://www.mozilla.org/en-US/firefox/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.8

VulDB Base Score: 5.0
VulDB Temp Score: 4.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Remote Code Execution
CWE: Unknown
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 246702
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-23999

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: mozilla.org

Timelineinfo

01/13/2021 🔍
06/25/2021 +162 days 🔍
06/25/2021 +0 days 🔍
08/09/2025 +1506 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: mozilla.org
Status: Confirmed

CVE: CVE-2021-23999 (🔍)
GCVE (CVE): GCVE-0-2021-23999
GCVE (VulDB): GCVE-100-177563

Entryinfo

Created: 06/25/2021 11:30
Updated: 08/09/2025 13:55
Changes: 06/25/2021 11:30 (37), 07/02/2021 09:46 (5), 08/09/2025 13:55 (17)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.