This document is work in progress

*What is CVSS*
    The Common Vulnerability Scoring System (CVSS) is an open, industry-standard framework used to measure and communicate the severity of software vulnerabilities, ranging from 0.0 to 10.0.

*Why we need this Document*
    It is important that FFmpeg CVEs have consistent and correct CVSS, not only for the obvious reason that one can recognize the severity of an issue at first glance.
    But also as these numbers form the basis of rewards paid in bug bounty systems. Inconsistent CVSS could lead to unfair payouts.

*What is this Document*
    Prior 2026, FFmpeg had no guideline about CVSS.
    This document describes how to select the CVSS for a FFmpeg related CVE. It currently only covers the Base Score.

*What is the CVSS Base Score*
    AV Attack Vector    (Network, Adjacent, Local, Physical)
    AC Attack Complexity (Low, High)
    PR Privileges Required (None, Low, High)
    UI User Interaction (None, Required)
    S  Scope (Unchanged, Changed)
    C  Confidentiality (None, Low, High)
    I  Integrity (None, Low, High)
    A  Availability (None, Low, High)


*Things people have set incorrectly*

Below are general guidelines and in specific cases other things may apply.

Attack Vector.
    Quote from https://www.first.org/cvss/v3.1/user-guide
        "Specifically, analysts should only score for Network or Adjacent when a vulnerability is bound to the network stack.
         Vulnerabilities which require user interaction to download or receive malicious content (which could also be delivered locally, e.g., via USB drives) should be scored as Local."

Availability.
    FFmpeg Crashes -> AVAILABILITY IMPACT: Low
    FFmpeg is frequently used as a short-lived, single-run process instead of a continuously running service that handles ongoing streams of user input. In that usage model, a crash usually causes only limited disruption.

User Interaction
    Please consider if an attacker can actually set the parameters required for an attack.
    In general arbitrary filter parameters cannot be set by an attacker and require the user/account owner/admin to set them
