Mozilla Firefox up to 86.x CSS Rule memory corruption

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 86.x. It has been rated as critical. Affected is an unknown function of the component CSS Rule Handler. This manipulation causes memory corruption. The identification of this vulnerability is CVE-2021-23983. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Mozilla Firefox up to 86.x (Web Browser) and classified as critical. Affected by this vulnerability is an unknown function of the component CSS Rule Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was shared 03/31/2021. It is possible to read the advisory at bugzilla.mozilla.org. This vulnerability is known as CVE-2021-23983. 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 pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/17/2025).

The vulnerability scanner Nessus provides a plugin with the ID 250128 (Linux Distros Unpatched Vulnerability : CVE-2021-23983), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 87.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (250128). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.2

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

NVD Base Score: 6.5
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
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: 250128
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-23983

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Firefox 87.0

Timelineinfo

01/13/2021 🔍
03/31/2021 +76 days 🔍
03/31/2021 +0 days 🔍
08/17/2025 +1600 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

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

CVE: CVE-2021-23983 (🔍)
GCVE (CVE): GCVE-0-2021-23983
GCVE (VulDB): GCVE-100-172039

Entryinfo

Created: 03/31/2021 22:01
Updated: 08/17/2025 11:14
Changes: 03/31/2021 22:01 (40), 04/07/2021 12:42 (5), 04/07/2021 12:49 (18), 08/17/2025 11:14 (17)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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