diff --git a/src/BuildCheck.UnitTests/EndToEndTests.cs b/src/BuildCheck.UnitTests/EndToEndTests.cs
index 358f8725b90..be460ba4062 100644
--- a/src/BuildCheck.UnitTests/EndToEndTests.cs
+++ b/src/BuildCheck.UnitTests/EndToEndTests.cs
@@ -172,6 +172,38 @@ public void EditorConfig_SeverityAppliedCorrectly(string BC0101Severity, string
         }
     }
 
+    [Fact]
+    public void CheckHasAccessToAllConfigs()
+    {
+        using (var env = TestEnvironment.Create())
+        {
+            string checkCandidatePath = Path.Combine(TestAssetsRootPath, "CheckCandidate");
+            string message = ": An extra message for the analyzer";
+            string severity = "warning";
+
+            // Can't use Transitive environment due to the need to dogfood local nuget packages.
+            AddCustomDataSourceToNugetConfig(checkCandidatePath);
+            string editorConfigName = Path.Combine(checkCandidatePath, EditorConfigFileName);
+            File.WriteAllText(editorConfigName, ReadEditorConfig(
+                new List<(string, string)>() { ("X01234", severity) },
+                new List<(string, (string, string))>
+                {
+                    ("X01234",("setMessage", message))
+                },
+                checkCandidatePath));
+
+            string projectCheckBuildLog = RunnerUtilities.ExecBootstrapedMSBuild(
+                $"{Path.Combine(checkCandidatePath, $"CheckCandidate.csproj")} /m:1 -nr:False -restore -check -verbosity:n", out bool success, timeoutMilliseconds: 1200_0000);
+            success.ShouldBeTrue();
+
+            projectCheckBuildLog.ShouldContain("warning X01234");
+            projectCheckBuildLog.ShouldContain(severity + message);
+
+            // Cleanup
+            File.Delete(editorConfigName);
+        }
+    }
+
     [Theory]
     [InlineData(true, true)]
     [InlineData(false, true)]
diff --git a/src/BuildCheck.UnitTests/TestAssets/CheckCandidate/.editorconfigtest b/src/BuildCheck.UnitTests/TestAssets/CheckCandidate/.editorconfigtest
index be166e833cd..0a06c0d3eb8 100644
--- a/src/BuildCheck.UnitTests/TestAssets/CheckCandidate/.editorconfigtest
+++ b/src/BuildCheck.UnitTests/TestAssets/CheckCandidate/.editorconfigtest
@@ -2,3 +2,4 @@ root = true
 
 [*.csproj]
 build_check.X01234.Severity=X01234Severity
+build_check.X01234.CustomConfig=dummy
diff --git a/src/BuildCheck.UnitTests/TestAssets/CustomCheck/Check1.cs b/src/BuildCheck.UnitTests/TestAssets/CustomCheck/Check1.cs
index 940791d3705..860f0138c42 100644
--- a/src/BuildCheck.UnitTests/TestAssets/CustomCheck/Check1.cs
+++ b/src/BuildCheck.UnitTests/TestAssets/CustomCheck/Check1.cs
@@ -17,9 +17,19 @@ public sealed class Check1 : Check
 
         public override IReadOnlyList<CheckRule> SupportedRules { get; } = new List<CheckRule>() { SupportedRule };
 
+        private string message = "Argument for the message format";
+
         public override void Initialize(ConfigurationContext configurationContext)
         {
+            var infraData = configurationContext.CheckConfig[0];
+            var customData = configurationContext.CustomConfigurationData[0].ConfigurationData;
             // configurationContext to be used only if check needs external configuration data.
+            if (customData is not null &&
+                configurationContext.CustomConfigurationData[0].RuleId == "X01234" &&
+                customData.TryGetValue("setmessage", out string? setMessage))
+            {
+                message = infraData.Severity + setMessage;
+            }
         }
 
         public override void RegisterActions(IBuildCheckRegistrationContext registrationContext)
@@ -32,7 +42,7 @@ private void EvaluatedPropertiesAction(BuildCheckDataContext<EvaluatedProperties
             context.ReportResult(BuildCheckResult.Create(
                 SupportedRule,
                 ElementLocation.EmptyLocation,
-                "Argument for the message format"));
+                message));
         }
     }
 }