The Common Vulnerability Scoring System (CVSS) has been updated to version 4.0, which has been formally announced by the Forum of Incident Response and Security Teams (FIRST). This update comes eight years after the debut of CVSS v3.0, the previous version of the system. At its 35th annual conference, which took place in June in Montreal, Canada, FIRST presented CVSS 4.0 to the attendees. The Common Vulnerability Scoring System, also known as CVSS, is a standardised framework for evaluating the severity of software vulnerabilities. It does this by assigning numerical scores or qualitative labels (such as low, medium, high, and critical) based on factors such as exploitability, impact on confidentiality, integrity, availability, and required privileges, with higher scores indicating more severe vulnerabilities.
The Common Vulnerability Scoring System, more often referred to as CVSS, is a methodology that provides a framework for evaluating and conveying the severity of software vulnerabilities. It offers a standardised way that organisations and security experts may use to analyse vulnerabilities based on the characteristics of the vulnerabilities, and then prioritise those vulnerabilities. The CVSS ratings provide assistance in making educated judgements on which vulnerabilities should be addressed first and how resources should be distributed for vulnerability management.
There have been several versions of CVSS, and each version has included enhancements and modifications that make it possible to more accurately evaluate the severity of vulnerabilities. The previous version, CVSS 3.1, has been upgraded to the current version, CVSS 4.0, which includes a number of significant updates and enhancements, including the following:
CVSS 4.0 has been designed with the goal of simplifying the scoring system and making it more accessible to users. It makes the scoring process more straightforward, which makes it simpler for security experts to grasp and put into practise.
Accurate Scoring: CVSS 4.0 includes enhancements in scoring to enable more accurate evaluations of vulnerabilities. These improvements were made possible by the introduction of new scoring methods. It improves the base, temporal, and environmental parameters such that a more accurate representation of the real effect of a vulnerability may be achieved.
Enhanced Metrics: It provides new metrics, such as Scope and Attack Vector, to offer more insights about the nature of the vulnerability and its effect on the system. Enhanced Metrics.
Formula: CVSS 4.0 comes with a revised formula that may be used to determine the total score on the CVSS scale. When paired with additional indicators, this formula provides a more accurate representation of the severity of vulnerabilities.
Contextual Information: When it comes to rating vulnerabilities, CVSS 4.0 strongly recommends making advantage of any available contextual information. This contributes to the provision of a vulnerability assessment that is more precise and relevant depending on certain deployment circumstances.
Increased Scoring Flexibility: The updated version offers an increased degree of scoring flexibility for vulnerabilities. Users are given the option to choose several temporal and environmental criteria, so that the data may more accurately represent their unique situations.
The Common Vulnerability Scoring System (CVSS) version 4.0 marks an advancement in vulnerability scoring and solves some of the restrictions that were present in prior versions. It seeks to offer a system for analysing and prioritising vulnerabilities that is both more accurate and easier to use, with the ultimate goal of assisting organisations in improving their security posture by concentrating on the most pressing problems. In order to improve their vulnerability management procedures, security professionals and organisations should get aware with CVSS 4.0 and consider implementing it.
Lets take an example of how you would use CVSS 4.0 to determine the degree of severity of a software vulnerability. For the sake of this example, we will employ a made-up vulnerability:
Vulnerability Description: An application contains a buffer overflow vulnerability, which an attacker can exploit to execute arbitrary code on the affected system.
Here’s how you would use CVSS 4.0 to assess the severity of this vulnerability:
- Attack Vector (AV): The vulnerability can be exploited via network (AV:N). The attacker does not need local access to the system.
- Attack Complexity (AC): The attack requires no special conditions (AC:LOW). It’s relatively easy to exploit.
- Privileges Required (PR): The attacker needs to gain elevated privileges (PR:HIGH). This makes it more challenging to exploit.
- User Interaction (UI): No user interaction is required (UI:NONE).
- Scope (S): The scope of the vulnerability is unchanged, and it doesn’t impact other components (S:UNCHANGED).
- Exploit Code Maturity (E): There is proof of concept code available, but no known exploits in the wild (E:POC).
- Remediation Level (RL): There is an official fix available (RL:OFFICIAL-FIX).
- Report Confidence (RC): The vulnerability has been confirmed by multiple sources (RC:HIGH).
Environmental Metrics (Specific to the organization’s setup):
- Modified Attack Vector (MAV): The organization’s security controls have made it harder for attackers to exploit this vulnerability (MAV:NETWORK).
- Modified Attack Complexity (MAC): The organization’s security measures have increased the difficulty of exploitation (MAC:HIGH).
- Modified Privileges Required (MPR): The organization’s security settings require lower privileges for successful exploitation (MPR:LOW).
Now, you can calculate the CVSS 4.0 score based on these metrics:
- Calculate the Base Score: In this case, it might be, for example, 7.8.
- Calculate the Temporal Score by considering the temporal metrics: Let’s say it’s 6.2.
- Calculate the Environmental Score, taking into account the environmental metrics and organization-specific factors: The final score might be 4.3.
The overall CVSS 4.0 score for this vulnerability would be the Environmental Score, which is 4.3 in this example. This score helps organizations understand the severity of the vulnerability in their specific context, considering the mitigations and configurations in place.
The higher the CVSS score, the more severe the vulnerability. Organizations can then prioritize addressing vulnerabilities with higher scores to improve their security posture. CVSS 4.0 offers more flexibility and a better representation of the vulnerability’s impact, taking into account various contextual factors.
Information security specialist, currently working as risk infrastructure specialist & investigator.
15 years of experience in risk and control process, security audit support, business continuity design and support, workgroup management and information security standards.