Common Vulnerability Scoring System(CVSS) is a numerical representation of the severity of a software vulnerability on a scale of 0-10. The final CVSS score is determined by the sub-categories from the 8 categories of options. This is a simplified version of the specification document by FirstOrg.
Attack Vector
This metric reflects the context by which vulnerability exploitation is possible.| Network | Remotely Exploitable via the Internet. |
| Adjacent | Attack via same shared physical or logical network. Example: Wi-Fi, Local IP subnet, Bluetooth |
| Local | Local access to system via keyboard, console or remotely like SSH or relies on user interaction such as Social Engineering. |
| Physical | Requires physical interaction with the vulnerable component. |
Attack Complexity
This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.| High | A successful attack depends on conditions beyond the attacker's control. Example: knowledge on target environment and configuration is required, mitigation techniques should be bypassed. |
| Low | The exploit do not rely on special conditions or configurations on a target environment. |
Privileges Required
This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.| High | Attacker is an authenticated/authorized with highest level of privileges. Example: administrator |
| Low | Attacker is an authenticated/authorized with low level privileges. |
| None | Attacker is an unauthenticated/unauthorized user. |
User Interaction
This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner. Here, user is a target or an authorized personnel associated with a target.| Required | Requires a user to take some action before the vulnerability can be exploited. Example: opening a link or a file. |
| None | The vulnerable system can be exploited without interaction from any user. |
Scope
This metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.| Changed | An exploited vulnerability can only affect resources managed by the same security authority. Example: HTML Injection (the code runs in the context of the web application) |
| Unchanged | An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. Example: Remote Command Execution on a web application (the command is executed on the web server) |
Confidentiality
This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.| High | Total loss of confidentiality. Example: plain-text password |
| Low | Some loss of confidentiality. Example: hashed password |
| None | No loss of confidentiality. |
Integrity
This metric measures the impact to integrity (trustworthiness and veracity of information) of a successfully exploited vulnerability.| High | Total loss of integrity. Example: all files can be modified |
| Low | Some loss of integrity. Example: limited modification of files |
| None | No loss of integrity. |
Availability
This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.| High | Total loss of availability. Example: permanent service interruption (repeated exploitation or persisted) |
| Low | Some loss of availability. Example: temporary service interruption |
| None | No loss of availability. |
Lastly, CVSS score is always debatable and different in different people's mind. References: https://www.first.org/cvss/specification-document