diff --git a/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/EnvironmentVariableNames.cs b/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/EnvironmentVariableNames.cs
index 134b1857f8fb..d9a0eac4845a 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/EnvironmentVariableNames.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/EnvironmentVariableNames.cs
@@ -60,6 +60,11 @@ internal class EnvironmentVariableNames
         /// </summary>
         public const string FallbackNugetFeeds = "CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_FALLBACK";
 
+        /// <summary>
+        /// Controls whether to include NuGet feeds from nuget.config files in the fallback restore logic.
+        /// </summary>
+        public const string AddNugetConfigFeedsToFallback = "CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_FALLBACK_INCLUDE_NUGET_CONFIG_FEEDS";
+
         /// <summary>
         /// Specifies the path to the nuget executable to be used for package restoration.
         /// </summary>
diff --git a/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackageRestorer.cs b/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackageRestorer.cs
index 5e556682df21..0204e9b7c408 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackageRestorer.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackageRestorer.cs
@@ -98,12 +98,14 @@ public HashSet<AssemblyLookupLocation> Restore()
             logger.LogInfo($"Checking NuGet feed responsiveness: {checkNugetFeedResponsiveness}");
             compilationInfoContainer.CompilationInfos.Add(("NuGet feed responsiveness checked", checkNugetFeedResponsiveness ? "1" : "0"));
 
+            HashSet<string>? explicitFeeds = null;
+
             try
             {
-                if (checkNugetFeedResponsiveness && !CheckFeeds())
+                if (checkNugetFeedResponsiveness && !CheckFeeds(out explicitFeeds))
                 {
                     // todo: we could also check the reachability of the inherited nuget feeds, but to use those in the fallback we would need to handle authentication too.
-                    var unresponsiveMissingPackageLocation = DownloadMissingPackagesFromSpecificFeeds();
+                    var unresponsiveMissingPackageLocation = DownloadMissingPackagesFromSpecificFeeds(explicitFeeds);
                     return unresponsiveMissingPackageLocation is null
                         ? []
                         : [unresponsiveMissingPackageLocation];
@@ -163,7 +165,7 @@ public HashSet<AssemblyLookupLocation> Restore()
             LogAllUnusedPackages(dependencies);
 
             var missingPackageLocation = checkNugetFeedResponsiveness
-                ? DownloadMissingPackagesFromSpecificFeeds()
+                ? DownloadMissingPackagesFromSpecificFeeds(explicitFeeds)
                 : DownloadMissingPackages();
 
             if (missingPackageLocation is not null)
@@ -173,13 +175,24 @@ public HashSet<AssemblyLookupLocation> Restore()
             return assemblyLookupLocations;
         }
 
-        private List<string> GetReachableFallbackNugetFeeds()
+        private List<string> GetReachableFallbackNugetFeeds(HashSet<string>? feedsFromNugetConfigs)
         {
             var fallbackFeeds = EnvironmentVariables.GetURLs(EnvironmentVariableNames.FallbackNugetFeeds).ToHashSet();
             if (fallbackFeeds.Count == 0)
             {
                 fallbackFeeds.Add(PublicNugetOrgFeed);
-                logger.LogInfo($"No fallback Nuget feeds specified. Using default feed: {PublicNugetOrgFeed}");
+                logger.LogInfo($"No fallback Nuget feeds specified. Adding default feed: {PublicNugetOrgFeed}");
+
+                var shouldAddNugetConfigFeeds = EnvironmentVariables.GetBooleanOptOut(EnvironmentVariableNames.AddNugetConfigFeedsToFallback);
+                logger.LogInfo($"Adding feeds from nuget.config to fallback restore: {shouldAddNugetConfigFeeds}");
+
+                if (shouldAddNugetConfigFeeds && feedsFromNugetConfigs?.Count > 0)
+                {
+                    // There are some feeds in `feedsFromNugetConfigs` that have already been checked for reachability, we could skip those.
+                    // But we might use different responsiveness testing settings when we try them in the fallback logic, so checking them again is safer.
+                    fallbackFeeds.UnionWith(feedsFromNugetConfigs);
+                    logger.LogInfo($"Using Nuget feeds from nuget.config files as fallback feeds: {string.Join(", ", feedsFromNugetConfigs.OrderBy(f => f))}");
+                }
             }
 
             logger.LogInfo($"Checking fallback Nuget feed reachability on feeds: {string.Join(", ", fallbackFeeds.OrderBy(f => f))}");
@@ -194,6 +207,8 @@ private List<string> GetReachableFallbackNugetFeeds()
                 logger.LogInfo($"Reachable fallback Nuget feeds: {string.Join(", ", reachableFallbackFeeds.OrderBy(f => f))}");
             }
 
+            compilationInfoContainer.CompilationInfos.Add(("Reachable fallback Nuget feed count", reachableFallbackFeeds.Count.ToString()));
+
             return reachableFallbackFeeds;
         }
 
@@ -272,9 +287,9 @@ private void RestoreProjects(IEnumerable<string> projects, out ConcurrentBag<Dep
             compilationInfoContainer.CompilationInfos.Add(("Failed project restore with package source error", nugetSourceFailures.ToString()));
         }
 
-        private AssemblyLookupLocation? DownloadMissingPackagesFromSpecificFeeds()
+        private AssemblyLookupLocation? DownloadMissingPackagesFromSpecificFeeds(HashSet<string>? feedsFromNugetConfigs)
         {
-            var reachableFallbackFeeds = GetReachableFallbackNugetFeeds();
+            var reachableFallbackFeeds = GetReachableFallbackNugetFeeds(feedsFromNugetConfigs);
             if (reachableFallbackFeeds.Count > 0)
             {
                 return DownloadMissingPackages(fallbackNugetFeeds: reachableFallbackFeeds);
@@ -623,10 +638,10 @@ private bool IsFeedReachable(string feed, int timeoutMilliSeconds, int tryCount,
             return (timeoutMilliSeconds, tryCount);
         }
 
-        private bool CheckFeeds()
+        private bool CheckFeeds(out HashSet<string> explicitFeeds)
         {
             logger.LogInfo("Checking Nuget feeds...");
-            var (explicitFeeds, allFeeds) = GetAllFeeds();
+            (explicitFeeds, var allFeeds) = GetAllFeeds();
 
             var excludedFeeds = EnvironmentVariables.GetURLs(EnvironmentVariableNames.ExcludedNugetFeedsFromResponsivenessCheck)
                 .ToHashSet() ?? [];
diff --git a/csharp/ql/integration-tests/all-platforms/standalone_resx/CompilationInfo.expected b/csharp/ql/integration-tests/all-platforms/standalone_resx/CompilationInfo.expected
index 1fbab458c34a..48cca2534533 100644
--- a/csharp/ql/integration-tests/all-platforms/standalone_resx/CompilationInfo.expected
+++ b/csharp/ql/integration-tests/all-platforms/standalone_resx/CompilationInfo.expected
@@ -3,6 +3,7 @@
 | Failed solution restore with package source error | 0.0 |
 | NuGet feed responsiveness checked | 1.0 |
 | Project files on filesystem | 1.0 |
+| Reachable fallback Nuget feed count | 1.0 |
 | Resource extraction enabled | 1.0 |
 | Restored .NET framework variants | 1.0 |
 | Restored projects through solution files | 0.0 |
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error/CompilationInfo.expected b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error/CompilationInfo.expected
index 81a44b5f8fd2..53ebd1016fb7 100644
--- a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error/CompilationInfo.expected
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error/CompilationInfo.expected
@@ -4,6 +4,7 @@
 | Fallback nuget restore | 1.0 |
 | NuGet feed responsiveness checked | 1.0 |
 | Project files on filesystem | 1.0 |
+| Reachable fallback Nuget feed count | 1.0 |
 | Resolved assembly conflicts | 7.0 |
 | Resource extraction enabled | 0.0 |
 | Restored .NET framework variants | 0.0 |
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error_timeout/CompilationInfo.expected b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error_timeout/CompilationInfo.expected
index 026a3d386e3c..777d615d99b9 100644
--- a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error_timeout/CompilationInfo.expected
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_error_timeout/CompilationInfo.expected
@@ -3,6 +3,7 @@
 | Inherited Nuget feed count | 1.0 |
 | NuGet feed responsiveness checked | 1.0 |
 | Project files on filesystem | 1.0 |
+| Reachable fallback Nuget feed count | 1.0 |
 | Resolved assembly conflicts | 7.0 |
 | Resource extraction enabled | 0.0 |
 | Restored .NET framework variants | 0.0 |
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.expected b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.expected
new file mode 100644
index 000000000000..2a530060edb2
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.expected
@@ -0,0 +1 @@
+| [...]/newtonsoft.json/13.0.3/lib/net6.0/Newtonsoft.Json.dll |
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.ql b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.ql
new file mode 100644
index 000000000000..79cf92de7911
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/Assemblies.ql
@@ -0,0 +1,11 @@
+import csharp
+
+private string getPath(Assembly a) {
+  not a.getCompilation().getOutputAssembly() = a and
+  exists(string s | s = a.getFile().getAbsolutePath() |
+    result = "[...]/" + s.substring(s.indexOf("newtonsoft.json"), s.length())
+  )
+}
+
+from Assembly a
+select getPath(a)
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.expected b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.expected
new file mode 100644
index 000000000000..9e869e1a6fb1
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.expected
@@ -0,0 +1,16 @@
+| All Nuget feeds reachable | 0.0 |
+| Fallback nuget restore | 1.0 |
+| NuGet feed responsiveness checked | 1.0 |
+| Project files on filesystem | 1.0 |
+| Reachable fallback Nuget feed count | 2.0 |
+| Resolved assembly conflicts | 7.0 |
+| Resource extraction enabled | 0.0 |
+| Restored .NET framework variants | 0.0 |
+| Solution files on filesystem | 1.0 |
+| Source files generated | 0.0 |
+| Source files on filesystem | 1.0 |
+| Successfully ran fallback nuget restore | 1.0 |
+| Unresolved references | 0.0 |
+| UseWPF set | 0.0 |
+| UseWindowsForms set | 0.0 |
+| WebView extraction enabled | 1.0 |
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.ql b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.ql
new file mode 100644
index 000000000000..073ffe3b224d
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/CompilationInfo.ql
@@ -0,0 +1,15 @@
+import csharp
+import semmle.code.csharp.commons.Diagnostics
+
+query predicate compilationInfo(string key, float value) {
+  key != "Resolved references" and
+  not key.matches("Compiler diagnostic count for%") and
+  exists(Compilation c, string infoKey, string infoValue | infoValue = c.getInfo(infoKey) |
+    key = infoKey and
+    value = infoValue.toFloat()
+    or
+    not exists(infoValue.toFloat()) and
+    key = infoKey + ": " + infoValue and
+    value = 1
+  )
+}
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/diagnostics.expected b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/diagnostics.expected
new file mode 100644
index 000000000000..5f298cd3a11f
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/diagnostics.expected
@@ -0,0 +1,42 @@
+{
+  "markdownMessage": "C# analysis with build-mode 'none' completed.",
+  "severity": "unknown",
+  "source": {
+    "extractorName": "csharp",
+    "id": "csharp/autobuilder/buildless/complete",
+    "name": "C# analysis with build-mode 'none' completed"
+  },
+  "visibility": {
+    "cliSummaryTable": true,
+    "statusPage": false,
+    "telemetry": true
+  }
+}
+{
+  "markdownMessage": "C# with build-mode set to 'none'. This means that all C# source in the working directory will be scanned, with build tools, such as Nuget and Dotnet CLIs, only contributing information about external dependencies.",
+  "severity": "note",
+  "source": {
+    "extractorName": "csharp",
+    "id": "csharp/autobuilder/buildless/mode-active",
+    "name": "C# with build-mode set to 'none'"
+  },
+  "visibility": {
+    "cliSummaryTable": true,
+    "statusPage": true,
+    "telemetry": true
+  }
+}
+{
+  "markdownMessage": "Found unreachable Nuget feed in C# analysis with build-mode 'none'. This may cause missing dependencies in the analysis.",
+  "severity": "warning",
+  "source": {
+    "extractorName": "csharp",
+    "id": "csharp/autobuilder/buildless/unreachable-feed",
+    "name": "Found unreachable Nuget feed in C# analysis with build-mode 'none'"
+  },
+  "visibility": {
+    "cliSummaryTable": true,
+    "statusPage": true,
+    "telemetry": true
+  }
+}
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/Program.cs b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/Program.cs
new file mode 100644
index 000000000000..39a9e95bb6e3
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/Program.cs
@@ -0,0 +1,6 @@
+class Program
+{
+    static void Main(string[] args)
+    {
+    }
+}
\ No newline at end of file
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/nuget.config b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/nuget.config
new file mode 100644
index 000000000000..6e4302658a95
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/nuget.config
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <clear />
+    <add key="x" value="https://www.nuget.org/api/v2/" />
+  </packageSources>
+</configuration>
\ No newline at end of file
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/proj.csproj b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/proj.csproj
new file mode 100644
index 000000000000..cef71796352c
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/proj/proj.csproj
@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net8.0</TargetFrameworks>
+  </PropertyGroup>
+
+  <Target Name="DeleteBinObjFolders" BeforeTargets="Clean">
+    <RemoveDir Directories=".\bin" />
+    <RemoveDir Directories=".\obj" />
+  </Target>
+
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+  </ItemGroup>
+</Project>
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/standalone.sln b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/standalone.sln
new file mode 100644
index 000000000000..493ab54b59a7
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/standalone.sln
@@ -0,0 +1,19 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.5.002.0
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "proj", "proj\proj.csproj", "{6ED00460-7666-4AE9-A405-4B6C8B02279A}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {4ED55A1C-066C-43DF-B32E-7EAA035985EE}
+	EndGlobalSection
+EndGlobal
diff --git a/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/test.py b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/test.py
new file mode 100644
index 000000000000..630dbfc06d47
--- /dev/null
+++ b/csharp/ql/integration-tests/posix-only/standalone_dependencies_nuget_config_fallback/test.py
@@ -0,0 +1,14 @@
+from create_database_utils import *
+from diagnostics_test_utils import *
+import os
+
+# os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK"] = "true"        # Nuget feed check is enabled by default
+os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK_TIMEOUT"] = "1"     # 1ms, the GET request should fail with such short timeout
+os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK_LIMIT"] = "1"       # Limit the count of checks to 1
+
+# Making sure the reachability test succeeds when doing a fallback restore:
+os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK_FALLBACK_TIMEOUT"] = "1000"
+os.environ["CODEQL_EXTRACTOR_CSHARP_BUILDLESS_NUGET_FEEDS_CHECK_FALLBACK_LIMIT"] = "5"
+
+run_codeql_database_create([], lang="csharp", extra_args=["--build-mode=none"])
+check_diagnostics()
\ No newline at end of file