[IntelliJ] Uncaught Exception Error retrieving vulnerability data from GitHub Security Advisory API java.net.ConnectException

IntelliJ build version: 2026.1.3 IU-261.25134.95
OS: Linux
JDK: JetBrains s.r.o. 25.0.3
Plugin version: 3.97.6-2026.1
Additional Info: None
Parent component:

com.intellij.openapi.wm.impl.IdeRootPane[,0,0,2560x1392,layout=com.intellij.openapi.wm.impl.IdeRootPane$CustomHeaderRootLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=449,maximumSize=,minimumSize=,preferredSize=]

Error message:

IdeaLoggingEvent[message=Error retrieving vulnerability data from GitHub Security Advisory API, throwable=java.net.ConnectException
	at <REDACTED: user-file-path>(HttpClientImpl.java:923)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.CVECheckService.retrieveVulnerabilityData(CVECheckService.java:312)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.CVECheckService.fetchCves(CVECheckService.java:241)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.CVECheckService.getCveUpgradeIssues(CVECheckService.java:200)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.CVECheckService.batchGetCVEIssues(CVECheckService.java:171)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.JavaUpgradeIssuesDetectionService.getCVEIssues(JavaUpgradeIssuesDetectionService.java:385)
	at com.microsoft.azure.toolkit.intellij.appmod.javaupgrade.service.JavaUp

Start by reading CVECheckService.retrieveVulnerabilityData at line 312 and the callers fetchCves, getCveUpgradeIssues, and batchGetCVEIssues. Reproduce the GitHub Security Advisory API connection failure in the IntelliJ plugin on Linux, then trace how the exception is surfaced and use the existing service tests, if present, to define the completed behavior.