Use related advisory severity to calculate exploitibility, weighted severity and risk scores

Signed-off-by: Tushar Goel <tushar.goel.dav@gmail.com>

Author: TG1999

vulnerabilities/pipelines/v2_improvers/compute_package_risk.py

@@ -7,7 +7,10 @@
 # See https://aboutcode.org for more information about nexB OSS projects.
 #
 from aboutcode.pipeline import LoopProgress
+from django.db.models import Prefetch
+from django.db.models import Q
 
+from vulnerabilities.models import AdvisorySeverity
 from vulnerabilities.models import AdvisoryV2
 from vulnerabilities.models import PackageV2
 from vulnerabilities.pipelines import VulnerableCodePipeline
@@ -35,7 +38,15 @@ def steps(cls):
     def compute_and_store_vulnerability_risk_score(self):
         affected_advisories = (
             AdvisoryV2.objects.filter(impacted_packages__affecting_packages__isnull=False)
-            .prefetch_related("references", "severities", "exploits")
+            .prefetch_related(
+                "references",
+                "severities",
+                "exploits",
+                Prefetch(
+                    "related_advisory_severities",
+                    queryset=AdvisoryV2.objects.prefetch_related("severities"),
+                ),
+            )
             .distinct()
         )
 
@@ -50,10 +61,13 @@ def compute_and_store_vulnerability_risk_score(self):
         batch_size = 5000
 
         for advisory in progress.iter(affected_advisories.iterator(chunk_size=batch_size)):
-            severities = advisory.severities.all()
             references = advisory.references.all()
             exploits = advisory.exploits.all()
 
+            severities = AdvisorySeverity.objects.filter(
+                Q(advisories=advisory) | Q(advisories__related_to_advisory_severities=advisory)
+            ).distinct()
+
             weighted_severity, exploitability = compute_vulnerability_risk_factors(
                 references=references,
                 severities=severities,

vulnerabilities/tests/pipelines/v2_improvers/test_relate_severities.py

@@ -8,7 +8,9 @@
 #
 
 import pytest
+from django.db.models import Q
 
+from vulnerabilities.models import AdvisorySeverity
 from vulnerabilities.models import AdvisoryV2
 from vulnerabilities.pipelines.v2_improvers.relate_severities import RelateSeveritiesPipeline
 from vulnerabilities.severity_systems import EPSS
@@ -42,6 +44,10 @@ def test_relate_severities_by_advisory_id():
     pipeline.relate_severities()
 
     assert base.related_advisory_severities.filter(id=severity_advisory.id).exists()
+    severities = AdvisorySeverity.objects.filter(
+        Q(advisories=base) | Q(advisories__related_to_advisory_severities=base)
+    ).distinct()
+    assert severities.filter(id=severity_advisory.severities.first().id).exists()
 
 
 @pytest.mark.django_db