feat: add a troubleshooting guide about a scheduler issue

Signed-off-by: Nicolas Crocfer <[email protected]>

Author: ncrocfer

docs/images/troubleshooting/clear-existing-tasks.png

@@ -104,3 +104,22 @@ Then run the installation again:
 
 !!!note
     `network: host` only works on Linux. If you're on macOS or Windows, make sure your Docker has proper internet access and DNS resolution.
+
+
+## How to Fix the CVE-2025-8875.json (KeyError: 'opencve') Bug
+
+This issue occurred because CISA added a new entry to its KEV list before MITRE had added it to the official CVE database. An issue has been raised [here](https://github.com/CVEProject/cvelistV5/issues/107).
+
+Because this behavior was undocumented, OpenCVE’s scheduler failed to parse the entry, resulting in the following error:
+
+![Troubleshooting KeyError OpenCVE](images/troubleshooting/key-error-opencve.png){.center style="width:100%"}
+
+The problem has been fixed in this [pull request](https://github.com/opencve/opencve/pull/604).
+
+You can upgrade OpenCVE and relaunch the failed DAG run in your Airflow scheduler instance. To do so, select it:
+
+![Troubleshooting Select DAGRun](images/troubleshooting/select-dagrun.png){.center style="width:100%"}
+
+Then click on the "Clear Existing Tasks" button:
+
+![Troubleshooting Clear Existing Tasks](images/troubleshooting/clear-existing-tasks.png){.center style="width:60%"}