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ahouseholder merged 2 commits into from
Sep 12, 2025
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Add a few explanatory callouts to EPSS howtos #949

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add a few explanatory question callouts in epss howtos
ahouseholder Sep 12, 2025
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Merge branch 'main' into update-epss-howto
ahouseholder Sep 12, 2025
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18 changes: 16 additions & 2 deletions docs/howto/using_epss/epss_percentiles.md
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Expand Up @@ -20,8 +20,10 @@ probability scores as one of a few different inputs to inform the
SSVC [Exploitation](../../reference/decision_points/exploitation.md) decision point.
This approach can be a useful approach to refine or augment the *input* to an existing SSVC decision model.

In this how-to, we'll explore a different approach that uses EPSS percentiles
as an amplifier to adjust the *output* of an existing SSVC decision model.
!!! question "What's in this How-To?"

In this how-to, we'll explore a different approach that uses EPSS percentiles
as an amplifier to adjust the *output* of an existing SSVC decision model.

## Starting Out with the SSVC Deployer Decision Model

Expand Down Expand Up @@ -147,6 +149,18 @@ And here is a JSON object representation of the decision table for programmatic
Now you can use this decision table in your SSVC implementation to adjust
the prioritization of vulnerabilities based on their EPSS percentiles.

!!! question "How can I sort work items within a given SSVC outcome category?"

While we don't usually recommend sorting within a given SSVC outcome category,
we recognize that some organizations may want to do this.

If you want to sort vulnerabilities within a given SSVC outcome (e.g., all vulnerabilities
that are classified as "Immediate"), you can use the raw EPSS probability score
as a secondary sorting key.
This way, even if multiple vulnerabilities fall into the same SSVC category,
you can still prioritize them based on their predicted likelihood of exploitation.


## Conclusion

In this how-to, we've demonstrated how to use EPSS percentiles as an amplifier
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6 changes: 6 additions & 0 deletions docs/howto/using_epss/epss_probability.md
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Expand Up @@ -4,6 +4,12 @@ SSVC users might want to combine exploitation-related information from multiple
sources into a single decision point for use downstream in a decision table
such as the SSVC [Deployer Decision Model](../deployer_tree.md).

!!! question "What's in this How-To?"

This How-To explores how to combine information from multiple sources
via SSVC Decision Points and Decision Tables to create a more nuanced view
of exploitation risk.

One such source is the [Exploit Prediction Scoring System](https://www.first.org/epss/)
([EPSS](https://www.first.org/epss)) probability score.

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