cve-update-nvd2-native: Use maximum CVSS score from all sources

The CVE check system was incorrectly reporting lower CVSS scores when
multiple scoring sources were available in the NVD database. This
occurred because the code only extracted the first element from the
metrics arrays, which could be a "Secondary" source with a lower score
rather than the "Primary" source or the highest available vendor score.

According to the CVSS v4.0 User Guide, "In situations where multiple
CVSS-B scores are applicable but only one is provided, the highest
CVSS-B score must be utilized." This follows the "reasonable worst-case"
principle established by the CVSS SIG.

This fix iterates through all available sources (v2, v3.0, v3.1, and
v4.0) and selects the maximum CVSS score to ensure the highest severity
is reported.

Fixes [YOCTO #15931]

References:
- https://www.first.org/cvss/v4.0/user-guide
- https://www.first.org/cvss/v3.1/user-guide
- https://www.first.org/cvss/v2/minutes/cvss-meeting-minutes-06202006.pdf

Signed-off-by: Het Patel <hetpat@cisco.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/recipes-core/meta/cve-update-nvd2-native.bb b/meta/recipes-core/meta/cve-update-nvd2-native.bb
index 8c8148dd92ddd778b114223dba6e87d8909c0ce4..41c34ba0d01cb1d5e9e0683bf445dd8c9514e703 100644 (file)
--- a/meta/recipes-core/meta/cve-update-nvd2-native.bb
+++ b/meta/recipes-core/meta/cve-update-nvd2-native.bb
@@ -350,32 +350,55 @@ def update_db(conn, elt):
         if desc['lang'] == 'en':
             cveDesc = desc['value']
     date = elt['cve']['lastModified']
+
+    # Extract maximum CVSS scores from all sources (Primary and Secondary)
+    cvssv2 = 0.0
     try:
-        accessVector = elt['cve']['metrics']['cvssMetricV2'][0]['cvssData']['accessVector']
-        vectorString = elt['cve']['metrics']['cvssMetricV2'][0]['cvssData']['vectorString']
-        cvssv2 = elt['cve']['metrics']['cvssMetricV2'][0]['cvssData']['baseScore']
+        # Iterate through all cvssMetricV2 entries and find the maximum score
+        for metric in elt['cve']['metrics']['cvssMetricV2']:
+            score = metric['cvssData']['baseScore']
+            if score > cvssv2:
+                cvssv2 = score
+                accessVector = metric['cvssData']['accessVector']
+                vectorString = metric['cvssData']['vectorString']
     except KeyError:
-        cvssv2 = 0.0
-    cvssv3 = None
+        pass
+
+    cvssv3 = 0.0
     try:
-        accessVector = accessVector or elt['cve']['metrics']['cvssMetricV30'][0]['cvssData']['attackVector']
-        vectorString = vectorString or elt['cve']['metrics']['cvssMetricV30'][0]['cvssData']['vectorString']
-        cvssv3 = elt['cve']['metrics']['cvssMetricV30'][0]['cvssData']['baseScore']
+        # Iterate through all cvssMetricV30 entries and find the maximum score
+        for metric in elt['cve']['metrics']['cvssMetricV30']:
+            score = metric['cvssData']['baseScore']
+            if score > cvssv3:
+                cvssv3 = score
+                accessVector = accessVector or metric['cvssData']['attackVector']
+                vectorString = vectorString or metric['cvssData']['vectorString']
     except KeyError:
         pass
+
     try:
-        accessVector = accessVector or elt['cve']['metrics']['cvssMetricV31'][0]['cvssData']['attackVector']
-        vectorString = vectorString or elt['cve']['metrics']['cvssMetricV31'][0]['cvssData']['vectorString']
-        cvssv3 = cvssv3 or elt['cve']['metrics']['cvssMetricV31'][0]['cvssData']['baseScore']
+        # Iterate through all cvssMetricV31 entries and find the maximum score
+        for metric in elt['cve']['metrics']['cvssMetricV31']:
+            score = metric['cvssData']['baseScore']
+            if score > cvssv3:
+                cvssv3 = score
+                accessVector = accessVector or metric['cvssData']['attackVector']
+                vectorString = vectorString or metric['cvssData']['vectorString']
     except KeyError:
         pass
-    cvssv3 = cvssv3 or 0.0
+
+    cvssv4 = 0.0
     try:
-        accessVector = accessVector or elt['cve']['metrics']['cvssMetricV40'][0]['cvssData']['attackVector']
-        vectorString = vectorString or elt['cve']['metrics']['cvssMetricV40'][0]['cvssData']['vectorString']
-        cvssv4 = elt['cve']['metrics']['cvssMetricV40'][0]['cvssData']['baseScore']
+        # Iterate through all cvssMetricV40 entries and find the maximum score
+        for metric in elt['cve']['metrics']['cvssMetricV40']:
+            score = metric['cvssData']['baseScore']
+            if score > cvssv4:
+                cvssv4 = score
+                accessVector = accessVector or metric['cvssData']['attackVector']
+                vectorString = vectorString or metric['cvssData']['vectorString']
     except KeyError:
-        cvssv4 = 0.0
+        pass
+
     accessVector = accessVector or "UNKNOWN"
     vectorString = vectorString or "UNKNOWN"