Linux Kernel Netfilter information disclosure

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.
6.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel. It has been declared as problematic. The affected element is an unknown function of the component Netfilter. Executing a manipulation can lead to information disclosure. This vulnerability is handled as CVE-2021-3773. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel (Operating System) (version now known). This vulnerability affects some unknown processing of the component Netfilter. 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.

The weakness was released 02/17/2022. The advisory is shared for download at bugzilla.redhat.com. This vulnerability was named CVE-2021-3773 since 09/06/2021. 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 08/16/2025). The MITRE ATT&CK project declares the attack technique as T1592.

The vulnerability scanner Nessus provides a plugin with the ID 250236 (Linux Distros Unpatched Vulnerability : CVE-2021-3773), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (250236). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.6
VulDB Meta Temp Score: 6.6

VulDB Base Score: 3.5
VulDB Temp Score: 3.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
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: 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: 250236
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-3773

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Timelineinfo

09/06/2021 🔍
02/17/2022 +164 days 🔍
02/17/2022 +0 days 🔍
08/16/2025 +1276 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: bugzilla.redhat.com
Status: Confirmed

CVE: CVE-2021-3773 (🔍)
GCVE (CVE): GCVE-0-2021-3773
GCVE (VulDB): GCVE-100-193276

Entryinfo

Created: 02/17/2022 08:23
Updated: 08/16/2025 19:20
Changes: 02/17/2022 08:23 (37), 02/19/2022 11:09 (1), 07/17/2024 13:04 (34), 08/16/2025 19:20 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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