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CVSS: How Reliable Is Its Score?

CVSS: How Reliable Is Its Score?

 By Charles Joseph | Cybersecurity Researcher
 Published on August 7th, 2023
This post was updated on November 25th, 2023

CVSS, standing for Common Vulnerability Scoring System, is an industry-standard used to assess the severity of computer system security vulnerabilities. It assists in rating the vulnerabilities helping understand their potential impact.

The scores range from 0 to 10, with 10 indicating the highest severity.

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How Reliable Is the CVSS?

The Common Vulnerability Scoring System (CVSS) provides a standardized framework for assessing the severity of security vulnerabilities. Its comprehensive metrics and consistent approach have made it a widely adopted tool in the cybersecurity industry.

However, the system has limitations, such as potential subjectivity in scoring and not capturing all nuances of real-world risks.

Some critics argue that it might lead organizations to overlook significant threats with slightly lower scores.

The temporal and environmental scores, which offer context-sensitive ratings, are also often underutilized (more on this later).

Overall, while CVSS is a valuable starting point, it’s essential to use it in conjunction with broader risk management strategies.

The CVSS Framework

The CVSS framework consists of three metric groups: Base, Temporal, and Environmental.

While the Base score focuses on the inherent properties of a vulnerability, the Temporal and Environmental scores allow for a more dynamic and context-specific assessment.

Temporal Score: This metric considers factors that change over time, such as the availability of an exploit or a patch. It reflects the current state and potential change in the risk associated with a vulnerability. For instance, a vulnerability might initially be hard to exploit, but the risk might increase as time progresses and more knowledge is available.

Environmental Score: This metric considers the specific circumstances of an organization or environment. For instance, a vulnerability might be present in a piece of software, but if that software isn’t used in a particular organization—or if it’s used but in a non-critical capacity—the real-world risk for that organization is different. The Environmental score allows organizations to adjust the severity based on their specific conditions, such as configuring the vulnerable software or the potential business impact of an exploit.

Despite their importance in providing a more holistic view of risk, these scores are often underutilized.

Many organizations rely heavily on the Base score to prioritize vulnerabilities.

This can lead to a less nuanced understanding of risk, potentially overlooking vulnerabilities that pose a significant threat in a specific context or over-prioritizing vulnerabilities that, due to environmental factors, might not be as urgent for a particular organization.

By not leveraging Temporal and Environmental scores, organizations may miss out on tailoring their vulnerability response to their unique situation and needs.

The History of the Common Vulnerability Scoring System

The Common Vulnerability Scoring System (CVSS) is a standard system used for rating the severity of security vulnerabilities in software.

The first version of CVSS, CVSSv1, was introduced by the National Infrastructure Advisory Council (NIAC) in 2004. It was an early attempt to standardize the evaluation process of vulnerabilities, providing a framework that could quantify the severity of a vulnerability, allowing for more consistent and useful evaluations.

CVSSv2 was released in 2007, introducing enhancements based on industry feedback. It became more detailed and accurate in scoring vulnerabilities, addressing many of the limitations and criticisms of the initial version.

By 2015, CVSSv3 was introduced by FIRST (Forum of Incident Response and Security Teams). This version refined the metric even further, introduced a few new metrics, and more closely aligned vulnerability scoring with the real-world risks they posed.

Given the system’s comprehensive nature and adaptability to feedback, it’s been widely adopted across the industry.

Today, various organizations, including software vendors, security vendors, and other entities within the cybersecurity community, use CVSS to evaluate and communicate the severity of vulnerabilities.

Its adoption has been widespread because it offers a standardized way to represent and communicate the potential impact of vulnerabilities, helping to prioritize response strategies and allocate resources more effectively.

CVSS Examples

1. Example – High Criticality Vulnerability

In this case, a hacker discovered a software system loophole. This loophole permits them to access personal and sensitive information available in the system. Situations like these pose significant risks to privacy and security of information.

The severity of this sort of vulnerability calls for immediate attention, which is why, after evaluation, such a predicament is given a CVSS rating of 7.5. A high score, especially one above 7.0, signifies that the vulnerability has the potential to cause considerable harm, i.e., it’s highly critical.

A swift course of action, such as implementing a security patch, must address the system flaw and prevent potential data breaches. This also reiterates the importance of regularly assessing and monitoring systems for vulnerabilities to avoid situations of data compromise.

2. Example – Low Severity Vulnerability

Here’s an instance where a vulnerability was detected within a system but is not easily exploitable. The circumstances under which it could become an issue are unusual and complex. So, the chance of it being a major problem is quite low.

After being evaluated, this system glitch is allocated a CVSS score of 2.0. A score in this range indicates a vulnerability with a low severity level. In other words, it is not a prime security concern.

Although not posing significant risks, a vulnerability with such a low CVSS score should not be outright ignored. It’s advisable to resolve such issues timely to maintain solid security measures and avoid the potential stacking of minor vulnerabilities that can cause larger security gaps over time.

3. Example – Extreme Severity Vulnerability

In this instance, an uncovered flaw in software opens a backdoor, permitting unauthorized users to alter the data. Such a situation can gravely compromise the integrity of the system’s data, posing a significant threat to security.

Due to the dire potential consequences, this issue is allocated a CVSS score of 10 after undergoing evaluation. This score stands at the apex of the severity scale and warns of a vulnerability that’s not just critical but extremely severe.

A CVSS score of 10 calls for immediate and strong measures to be enacted. Given the vulnerability allows unauthorized data modifications, developers must swiftly rectify the issue to reinstall secure data handling. This score also underscores the imperative nature of rigorous, ongoing system checks to promptly identify and address such critical vulnerabilities.


The use of the Common Vulnerability Scoring System (CVSS) provides an efficient way to assess and prioritize the severity of system vulnerabilities. By properly understanding and applying the scores, organizations can respond to cyber threats more effectively and maintain a higher level of data security.

Key Takeaways

  • CVSS stands for Common Vulnerability Scoring System, which is a standard used to assess the severity of computer system security vulnerabilities.
  • CVSS scores range from 0 to 10, with 10 being the highest severity level, indicating an extreme risk.
  • The scores help understand vulnerability threats and their potential impact, aiding organizations to prioritize their addressing.
  • Even vulnerabilities with low CVSS scores should not be ignored, as they could lead to larger security gaps over time.
  • A high CVSS score, such as 7.5 or 10, calls for immediate attention and response.

Related Questions

#1. What actions should be taken for a vulnerability with a high CVSS score?

For high CVSS scores, immediate actions such as implementing security patches or updates should be taken to rectify the vulnerability and safeguard the system infrastructure.

#2. Are vulnerabilities with low CVSS scores a cause of concern?

While low CVSS scores indicate minor severity, such vulnerabilities should not be dismissed. Over time, multiple minor vulnerabilities could collectively result in significant security gaps.

#3. Can the CVSS score of a vulnerability change over time?

Yes, a CVSS score can change over time. If the vulnerability becomes easier or harder to exploit, this may alter the CVSS score, redefining the severity.

#4. Who should be concerned about CVSS scores?

CVSS scores are critical information for IT professionals, system administrators, and any individual or organization responsible for managing cyber risks and maintaining secure systems.

#5. How often should a system be checked for vulnerabilities?

For maintaining an optimal level of security, regular and continuous checks for vulnerabilities should be performed, regardless of the system’s history with security incidents.

"Amateurs hack systems, professionals hack people."
-- Bruce Schneier, a renown computer security professional
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