Merge branch 'YashaRise-vulnerability-measures-documentation' into 'master'

Create vulnerability measures documentation with EPSS

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/172508



Merged-by: Russell Dickenson <rdickenson@gitlab.com>
Approved-by: John Crowley <jcrowley@gitlab.com>
Approved-by: Russell Dickenson <rdickenson@gitlab.com>
Co-authored-by: Yasha Rise <yrise@gitlab.com>
Co-authored-by: Marcel Amirault <mamirault@gitlab.com>

doc/user/application_security/vulnerabilities/risk_assessment_data.md

+---
+stage: Application Security Testing
+group: Composition Analysis
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://handbook.gitlab.com/handbook/product/ux/technical-writing/#assignments
+---
+
+# Vulnerability risk assessment data
+
+Use vulnerability risk data to help assess the potential impact to your environment.
+
+Vulnerability risk data includes:
+
+- Severity - [Common Vulnerability Scoring System (CVSS)](severities.md)
+- Likelihood of exploitation - [EPSS](#epss)
+- Presence of known exploits - [KEV](#kev)
+
+With multiple data points you can better prioritize remediation and mitigation actions.
+For example, a vulnerability with medium severity and a high EPSS score may require mitigation
+sooner than a vulnerability with a high severity and a low EPSS score.
+
+## EPSS
+
+> - Introduced in GitLab 17.4 [with flags](../../../administration/feature_flags.md) named `epss_querying` (in issue [470835](https://gitlab.com/gitlab-org/gitlab/-/issues/470835)) and `epss_intgestion` (in issue [467672](https://gitlab.com/gitlab-org/gitlab/-/issues/467672)). Disabled by default.
+> - Renamed to `cve_enrichment_querying` and `cve_enrichment_ingestion` respectively and [enabled on GitLab.com](https://gitlab.com/gitlab-org/gitlab/-/issues/481431) in GitLab 17.6.
+
+FLAG:
+The availability of this feature is controlled by a feature flag.
+For more information, see the history.
+
+[Exploit Prediction Scoring System (EPSS)](https://www.first.org/epss) provides an estimate of the likelihood a vulnerability (namely [CVE](https://www.cve.org/)) will be exploited in the next 30 days. EPSS gives each CVE a score between 0 to 1 (equivalent to 0% to 100%).
+
+### Querying EPSS
+
+You can query the EPSS score of vulnerabilities by using the [GraphQL API](../../../api/graphql/index.md). Scores are attached to CVEs and are rounded to the second decimal digit.
+
+The `cveEnrichment` field in the GitLab API model contains the CVE ID and an EPSS score for a given CVE. It is accessible through the `Vulnerability` type.
+
+For example, the following GraphQL query returns all vulnerabilities in a given project and
+their EPSS scores. Run the query in the
+[GraphQL explorer](../../../api/graphql/index.md#interactive-graphql-explorer) or any other GraphQL client.
+
+```graphql
+{
+  project(fullPath: "<full/path/to/project>") {
+    vulnerabilities {
+      nodes {
+        identifiers {
+          externalId
+          externalType
+        }
+        cveEnrichment {
+          epssScore
+          cve
+        }
+      }
+    }
+  }
+}
+```
+
+Sample output:
+
+```json
+{
+  "data": {
+    "project": {
+      "vulnerabilities": {
+        "nodes": [
+          {
+            "identifiers": [
+              {
+                "externalId": "CVE-2024-37371",
+                "externalType": "cve"
+              }
+            ],
+            "cveEnrichment": {
+              "epssScore": 0,
+              "cve": "CVE-2024-37371"
+            }
+          },
+          {
+            "identifiers": [
+              {
+                "externalId": "CVE-2024-5171",
+                "externalType": "cve"
+              }
+            ],
+            "cveEnrichment": {
+              "epssScore": 0.02,
+              "cve": "CVE-2024-5171"
+            }
+          }
+        ]
+      }
+    }
+  },
+  "correlationId": "..."
+}
+```
+
+## KEV
+
+[CISA Known Exploited Vulnerabilities (KEV) catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog) is a catalog of vulnerabilities that are known to have been exploited. It is crucial to remediate these vulnerabilities if you find them in your environment because there are documented cases of attacks using these vulnerabilities and the exploitation method is likely known to attackers.
+
+Support for KEV is proposed in [epic 11912](https://gitlab.com/groups/gitlab-org/-/epics/11912).