diff --git a/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj b/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
index da7430871..404f357ad 100644
--- a/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
+++ b/Duplicati/Library/Modules/Builtin/Duplicati.Library.Modules.Builtin.csproj
@@ -16,7 +16,7 @@
     <PackageReference Include="Handlebars.Net" Version="2.1.6" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="MailKit" Version="4.12.1" />
-    <PackageReference Include="MimeKit" Version="4.12.0" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/proprietary/Office365/Duplicati.Proprietary.Office365.csproj b/proprietary/Office365/Duplicati.Proprietary.Office365.csproj
index 7452a7e1e..94d125c72 100644
--- a/proprietary/Office365/Duplicati.Proprietary.Office365.csproj
+++ b/proprietary/Office365/Duplicati.Proprietary.Office365.csproj
@@ -12,7 +12,7 @@
     <ProjectReference Include="../../Duplicati/Library/AutoUpdater/Duplicati.Library.AutoUpdater.csproj" />
     <ProjectReference Include="../../Duplicati/Library/Utility/Duplicati.Library.Utility.csproj" />
     <ProjectReference Include="../LicenseChecker/Duplicati.Proprietary.LicenseChecker.csproj" />
-    <PackageReference Include="MimeKit" Version="4.12.0" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
     <PackageReference Include="jose-jwt" Version="5.2.0" />
   </ItemGroup>