diff --git a/eng/Build.ps1 b/eng/Build.ps1
index 41a52df6395..01ff6313626 100644
--- a/eng/Build.ps1
+++ b/eng/Build.ps1
@@ -253,7 +253,7 @@ function Process-Arguments() {
     }
 
     foreach ($property in $properties) {
-        if (!$property.StartsWith("/p:", "InvariantCultureIgnoreCase")) {
+        if (!$property.StartsWith("/p:", "InvariantCultureIgnoreCase") -and !$property.StartsWith("/clp:", "InvariantCultureIgnoreCase")) {
             Write-Host "Invalid argument: $property"
             Print-Usage
             exit 1
diff --git a/eng/Version.Details.props b/eng/Version.Details.props
index 58ea96baca0..81c65b28de8 100644
--- a/eng/Version.Details.props
+++ b/eng/Version.Details.props
@@ -24,9 +24,9 @@ This file should be imported by eng/Versions.props
     <MicrosoftCodeAnalysisCSharpPackageVersion>5.10.0-1.26365.3</MicrosoftCodeAnalysisCSharpPackageVersion>
     <MicrosoftCodeAnalysisEditorFeaturesPackageVersion>5.10.0-1.26365.3</MicrosoftCodeAnalysisEditorFeaturesPackageVersion>
     <MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>5.10.0-1.26365.3</MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion>
-    <MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion>5.10.0-1.26365.3</MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion>
     <MicrosoftCodeAnalysisFeaturesPackageVersion>5.10.0-1.26365.3</MicrosoftCodeAnalysisFeaturesPackageVersion>
     <MicrosoftVisualStudioLanguageServicesPackageVersion>5.10.0-1.26365.3</MicrosoftVisualStudioLanguageServicesPackageVersion>
+    <MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion>5.10.0-1.26365.3</MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion>
     <!-- dotnet-runtime dependencies -->
     <SystemCollectionsImmutablePackageVersion>10.0.8</SystemCollectionsImmutablePackageVersion>
     <SystemCompositionPackageVersion>10.0.8</SystemCompositionPackageVersion>
@@ -55,9 +55,9 @@ This file should be imported by eng/Versions.props
     <MicrosoftCodeAnalysisCSharpVersion>$(MicrosoftCodeAnalysisCSharpPackageVersion)</MicrosoftCodeAnalysisCSharpVersion>
     <MicrosoftCodeAnalysisEditorFeaturesVersion>$(MicrosoftCodeAnalysisEditorFeaturesPackageVersion)</MicrosoftCodeAnalysisEditorFeaturesVersion>
     <MicrosoftCodeAnalysisEditorFeaturesTextVersion>$(MicrosoftCodeAnalysisEditorFeaturesTextPackageVersion)</MicrosoftCodeAnalysisEditorFeaturesTextVersion>
-    <MicrosoftVisualStudioLanguageServicesExternalAccessVersion>$(MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion)</MicrosoftVisualStudioLanguageServicesExternalAccessVersion>
     <MicrosoftCodeAnalysisFeaturesVersion>$(MicrosoftCodeAnalysisFeaturesPackageVersion)</MicrosoftCodeAnalysisFeaturesVersion>
     <MicrosoftVisualStudioLanguageServicesVersion>$(MicrosoftVisualStudioLanguageServicesPackageVersion)</MicrosoftVisualStudioLanguageServicesVersion>
+    <MicrosoftVisualStudioLanguageServicesExternalAccessVersion>$(MicrosoftVisualStudioLanguageServicesExternalAccessPackageVersion)</MicrosoftVisualStudioLanguageServicesExternalAccessVersion>
     <!-- dotnet-runtime dependencies -->
     <SystemCollectionsImmutableVersion>$(SystemCollectionsImmutablePackageVersion)</SystemCollectionsImmutableVersion>
     <SystemCompositionVersion>$(SystemCompositionPackageVersion)</SystemCompositionVersion>
diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index b3eb553ea2c..b760b48c112 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
-  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="cb8306a63c5cf24e9381108a3a9eb58907fd0f60" BarId="323048" />
+  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="aedf05ae4b6c7f74f789e64a0a8d9d169414f04f" BarId="325626" />
   <ProductDependencies>
     <Dependency Name="Microsoft.Build" Version="18.10.0-preview-26357-08">
       <Uri>https://github.com/dotnet/msbuild</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index 773e10bfb8c..febf548022a 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -14,8 +14,8 @@
   <PropertyGroup>
     <!-- Don't use the built in support for pre-release iteration. The nuget repack task doesn't support
          the iteration format at the moment. https://github.com/dotnet/arcade/issues/15919 -->
-    <FSharpPreReleaseIteration>7</FSharpPreReleaseIteration>
-    <PreReleaseVersionLabel>preview$(FSharpPreReleaseIteration)</PreReleaseVersionLabel>
+    <FSharpPreReleaseIteration>1</FSharpPreReleaseIteration>
+    <PreReleaseVersionLabel>rc$(FSharpPreReleaseIteration)</PreReleaseVersionLabel>
     <!-- F# Version components -->
     <FSMajorVersion>11</FSMajorVersion>
     <FSMinorVersion>0</FSMinorVersion>
diff --git a/eng/build.sh b/eng/build.sh
index 0e63dda50fe..7e0d6dd2a87 100755
--- a/eng/build.sh
+++ b/eng/build.sh
@@ -194,6 +194,9 @@ while [[ $# > 0 ]]; do
     /p:*)
       properties+=("$1")
       ;;
+    /clp:*)
+      properties+=("$1")
+      ;;
     *)
       echo "Invalid argument: $1"
       usage
diff --git a/src/Microsoft.CommonLanguageServerProtocol.Framework.Proxy/Microsoft.CommonLanguageServerProtocol.Framework.Proxy.csproj b/src/Microsoft.CommonLanguageServerProtocol.Framework.Proxy/Microsoft.CommonLanguageServerProtocol.Framework.Proxy.csproj
index 063c6b6ae0d..2eaa653e8b6 100644
--- a/src/Microsoft.CommonLanguageServerProtocol.Framework.Proxy/Microsoft.CommonLanguageServerProtocol.Framework.Proxy.csproj
+++ b/src/Microsoft.CommonLanguageServerProtocol.Framework.Proxy/Microsoft.CommonLanguageServerProtocol.Framework.Proxy.csproj
@@ -8,6 +8,8 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.CommonLanguageServerProtocol.Framework" PrivateAssets="all" />
+		<!-- Pin the transitive MessagePack (via Microsoft.CommonLanguageServerProtocol.Framework) to a patched version. Older versions (< 2.5.301) have known vulnerabilities (NU1902/NU1903). -->
+		<PackageReference Include="MessagePack" PrivateAssets="all" />
 		<!-- Pinned below the central version to match the LSP framework's VS 17.x baseline. -->
 		<PackageReference Include="Microsoft.VisualStudio.Threading" VersionOverride="17.12.21" />
 	</ItemGroup>