diff --git a/src/libraries/tests.proj b/src/libraries/tests.proj
index 4de29857494251..c9711aff2d5bfb 100644
--- a/src/libraries/tests.proj
+++ b/src/libraries/tests.proj
@@ -183,10 +183,8 @@
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime\tests\System.IO.FileSystem.Tests\DisabledFileLockingTests\System.IO.FileSystem.DisabledFileLocking.Tests.csproj" />
   </ItemGroup>
 
-  <!-- https://github.com/dotnet/runtime/issues/125495 - These tests are disabled on browser/CoreCLR because of crashes and test failures. -->
+  <!-- https://github.com/dotnet/runtime/issues/125495 - Some test suites are disabled on browser/CoreCLR (e.g., long running suites). -->
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(RuntimeFlavor)' == 'CoreCLR' and '$(RunDisabledWasmTests)' != 'true'">
-    <!-- test failures -->
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Formats.Nrbf\tests\System.Formats.Nrbf.Tests.csproj" />
     <!-- long running suites -->
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Linq\tests\System.Linq.Tests.csproj" />
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Memory\tests\System.Memory.Tests.csproj" />
diff --git a/src/mono/browser/build/BrowserWasmApp.CoreCLR.targets b/src/mono/browser/build/BrowserWasmApp.CoreCLR.targets
index e94f759abc4f69..b0d74340c6c7d9 100644
--- a/src/mono/browser/build/BrowserWasmApp.CoreCLR.targets
+++ b/src/mono/browser/build/BrowserWasmApp.CoreCLR.targets
@@ -178,6 +178,122 @@
                      '$(WasmBuildingForNestedPublish)' != 'true' and
                      '$(UsingBrowserRuntimeWorkload)' != 'true'" />
 
+  <!-- The SDK declares this in Microsoft.NET.ConflictResolution.targets for every Microsoft.NET.Sdk build
+       (which every browser-wasm app is). Re-declare it here, guarded, so the task resolves on user systems
+       regardless of import order; the guard also lets the target degrade gracefully where the SDK build
+       tasks assembly is unavailable. -->
+  <UsingTask TaskName="ResolvePackageFileConflicts"
+             AssemblyFile="$(MicrosoftNETBuildTasksAssembly)"
+             Condition="'$(MicrosoftNETBuildTasksAssembly)' != '' and Exists('$(MicrosoftNETBuildTasksAssembly)')" />
+
+  <!-- ==================== Resolve runtime-pack vs app-local assembly conflicts by version ====================
+
+    For a self-contained browser-wasm app, @(ReferenceCopyLocalPaths) can contain two copies of the
+    same assembly: the runtime-pack copy (under $(MicrosoftNetCoreAppRuntimePackDir)) and an app-local
+    copy referenced out-of-band at a different version. ComputeWasmBuildAssets dedupes the webcil bundle
+    candidates by relative path (first-wins, version-blind), so the wrong copy can shadow the other one
+    in _framework. The canonical case is System.Runtime.Serialization.Formatters: the shared framework
+    ships a non-functional 8.1.0.0 stub while the app references the functional 11.0.0.0 build, so an
+    Assembly.Load for 11.0.0.0 then fails with FileNotFoundException.
+
+    Resolve the shadowed pairs with the SDK's own conflict resolver (ResolvePackageFileConflicts) — the
+    same task SDK publish uses (Microsoft.NET.ConflictResolution.targets) — so the higher AssemblyVersion
+    wins, exactly as a desktop self-contained publish would. This is version-based, not an unconditional
+    app-local preference: when the runtime-pack copy is the higher version it is the one that is kept. The
+    wasm build path normally never reaches that resolver for runtime-pack files, which is why the stub
+    leaks into _framework. We feed the resolver only the same-named runtime-pack/app-local pairs that deploy
+    to the _framework root (no culture subdirectory) and drop whichever copies it discards; assemblies that
+    exist in just one place, and culture-specific satellites, are untouched.
+
+    Robustness on user systems: ResolvePackageFileConflicts ships in the .NET SDK, so it is present for any
+    Microsoft.NET.Sdk browser-wasm build (in-repo or on a user machine). If the SDK build tasks assembly is
+    somehow unavailable, fall back to "app-local wins" (drop the shadowed runtime-pack copies) so the fix
+    still applies — matching how a self-contained app loads assemblies.
+
+    DependsOnTargets=ResolveReferences guarantees @(ReferenceCopyLocalPaths) is populated before we prune;
+    _GatherWasmFilesToBuild (unlike _ComputeWasmBuildCandidates) does not pull it in on its own.
+  -->
+  <Target Name="_CoreCLRResolveRuntimePackVsAppLocalConflicts"
+          BeforeTargets="_ComputeWasmBuildCandidates;_GatherWasmFilesToBuild"
+          DependsOnTargets="ResolveReferences"
+          Condition="'$(IsBrowserWasmProject)' == 'true'">
+    <PropertyGroup>
+      <!-- Resolve the runtime pack dir the same way the WebAssembly SDK does (Browser.targets): prefer
+           the property, fall back to the ResolvedRuntimePack metadata (WBT/Helix-created projects leave
+           the property empty). A browser-wasm CoreCLR app resolves exactly one runtime pack
+           (Microsoft.NETCore.App), so the metadata expansion is unambiguous — the same single-pack
+           assumption the SDK's own Browser.targets relies on. Normalize once (full path + trailing slash)
+           so the StartsWith checks below reliably match %(FullPath), which uses native separators. All
+           comparisons use the OrdinalIgnoreCase StringComparison so a casing difference between the
+           property and the enumerated item paths (common on case-insensitive filesystems) cannot silently
+           misclassify a copy. Path membership uses StartsWith(string, StringComparison); name membership
+           uses IndexOf(string, StringComparison) with the "!= -1" test kept OUTSIDE the $() (MSBuild's
+           property-function expander returns the int index but rejects a trailing comparison operator
+           inside the $(), which is the MSB4184 trap). Both overloads exist on .NET Framework MSBuild;
+           the Contains(string, StringComparison) overload does not, so it is avoided. -->
+      <_CoreCLRRuntimePackDir>$(MicrosoftNetCoreAppRuntimePackDir)</_CoreCLRRuntimePackDir>
+      <_CoreCLRRuntimePackDir Condition="'$(_CoreCLRRuntimePackDir)' == ''">%(ResolvedRuntimePack.PackageDirectory)</_CoreCLRRuntimePackDir>
+      <_CoreCLRRuntimePackDir Condition="'$(_CoreCLRRuntimePackDir)' != ''">$([MSBuild]::NormalizeDirectory('$(_CoreCLRRuntimePackDir)'))</_CoreCLRRuntimePackDir>
+    </PropertyGroup>
+    <ItemGroup Condition="'$(_CoreCLRRuntimePackDir)' != ''">
+      <!-- Split copy-local managed assemblies into app-local vs runtime-pack copies. Restrict both sets to
+           assemblies that deploy to the _framework root: ComputeWasmBuildAssets keys the bundle on a culture-
+           qualified RelativePath (_framework/<culture>/<name> for satellites, _framework/<name> otherwise), so
+           same-named satellites in different cultures never actually collide. Matching the conflict set only by
+           file name would wrongly pair them, so we exclude anything with a culture/subdirectory (empty
+           DestinationSubDirectory and Culture == root deployment). Satellite-vs-satellite version skew is out of
+           scope here and is left to the downstream first-wins dedup. -->
+      <_CoreCLRAppLocalAssembly Include="@(ReferenceCopyLocalPaths)"
+                                Condition="'%(Extension)' == '.dll' and '%(ReferenceCopyLocalPaths.DestinationSubDirectory)' == '' and '%(ReferenceCopyLocalPaths.Culture)' == '' and !$([System.String]::Copy('%(FullPath)').StartsWith('$(_CoreCLRRuntimePackDir)', System.StringComparison.OrdinalIgnoreCase))" />
+      <_CoreCLRRuntimePackAssembly Include="@(ReferenceCopyLocalPaths)"
+                                   Condition="'%(Extension)' == '.dll' and '%(ReferenceCopyLocalPaths.DestinationSubDirectory)' == '' and '%(ReferenceCopyLocalPaths.Culture)' == '' and $([System.String]::Copy('%(FullPath)').StartsWith('$(_CoreCLRRuntimePackDir)', System.StringComparison.OrdinalIgnoreCase))" />
+    </ItemGroup>
+    <PropertyGroup Condition="'$(_CoreCLRRuntimePackDir)' != ''">
+      <!-- ;-delimited name lists wrapped in leading/trailing ';' so an IndexOf of ';name;' below is an
+           exact whole-name membership test (never a substring of a longer name). -->
+      <_CoreCLRAppLocalAssemblyNames>;@(_CoreCLRAppLocalAssembly->'%(FileName)%(Extension)');</_CoreCLRAppLocalAssemblyNames>
+      <_CoreCLRRuntimePackAssemblyNames>;@(_CoreCLRRuntimePackAssembly->'%(FileName)%(Extension)');</_CoreCLRRuntimePackAssemblyNames>
+    </PropertyGroup>
+    <ItemGroup Condition="'$(_CoreCLRRuntimePackDir)' != ''">
+      <!-- The conflict set: copies of the same file name present in BOTH the runtime pack and app-local. -->
+      <_CoreCLRConflictCandidate Include="@(_CoreCLRRuntimePackAssembly)"
+                                 Condition="$(_CoreCLRAppLocalAssemblyNames.IndexOf(';%(FileName)%(Extension);', System.StringComparison.OrdinalIgnoreCase)) != -1" />
+      <_CoreCLRConflictCandidate Include="@(_CoreCLRAppLocalAssembly)"
+                                 Condition="$(_CoreCLRRuntimePackAssemblyNames.IndexOf(';%(FileName)%(Extension);', System.StringComparison.OrdinalIgnoreCase)) != -1" />
+    </ItemGroup>
+
+    <!-- Version-based resolution (parity with SDK publish/desktop): keep the higher AssemblyVersion.
+         PreferredPackages mirrors the SDK publish call (_HandlePackageFileConflictsForPublish) so that an
+         exact AssemblyVersion+FileVersion tie is broken the same way publish breaks it (preferring the
+         framework package) instead of being left to the downstream first-wins dedup. The property is
+         populated by ResolveTargetingPackAssets, which runs as part of our ResolveReferences dependency. -->
+    <ResolvePackageFileConflicts Condition="'@(_CoreCLRConflictCandidate)' != '' and Exists('$(MicrosoftNETBuildTasksAssembly)')"
+                                 ReferenceCopyLocalPaths="@(_CoreCLRConflictCandidate)"
+                                 PreferredPackages="$(PackageConflictPreferredPackages)">
+      <Output TaskParameter="ReferenceCopyLocalPathsWithoutConflicts" ItemName="_CoreCLRConflictWinners" />
+    </ResolvePackageFileConflicts>
+    <!-- Drop the discarded copies. Mirror the SDK's _HandlePackageFileConflicts (remove every candidate, then
+         re-add the winners) instead of removing a computed "loser" subset by identity: @(ReferenceCopyLocalPaths)
+         removal matches on ItemSpec only, so an Exclude-derived loser list is fragile if an ItemSpec ever repeats
+         with different metadata. ReferenceCopyLocalPathsWithoutConflicts carries the winners' full metadata, so
+         re-including them is lossless, and removing both candidate copies first guarantees the loser is gone. -->
+    <ItemGroup Condition="'@(_CoreCLRConflictCandidate)' != '' and Exists('$(MicrosoftNETBuildTasksAssembly)')">
+      <ReferenceCopyLocalPaths Remove="@(_CoreCLRConflictCandidate)" />
+      <ReferenceCopyLocalPaths Include="@(_CoreCLRConflictWinners)" />
+    </ItemGroup>
+
+    <!-- Fallback when the SDK conflict-resolution task is unavailable: prefer app-local (copy-local wins). Same
+         root-only restriction as the split above so a runtime-pack satellite is never removed on a bare file-name
+         match against an unrelated app-local satellite in a different culture. -->
+    <ItemGroup Condition="'$(_CoreCLRRuntimePackDir)' != '' and '@(_CoreCLRConflictCandidate)' != '' and !Exists('$(MicrosoftNETBuildTasksAssembly)')">
+      <ReferenceCopyLocalPaths Remove="@(ReferenceCopyLocalPaths)"
+                               Condition="'%(Extension)' == '.dll'
+                                          and '%(ReferenceCopyLocalPaths.DestinationSubDirectory)' == '' and '%(ReferenceCopyLocalPaths.Culture)' == ''
+                                          and $([System.String]::Copy('%(FullPath)').StartsWith('$(_CoreCLRRuntimePackDir)', System.StringComparison.OrdinalIgnoreCase))
+                                          and $(_CoreCLRAppLocalAssemblyNames.IndexOf(';%(FileName)%(Extension);', System.StringComparison.OrdinalIgnoreCase)) != -1" />
+    </ItemGroup>
+  </Target>
+
   <!-- ======================== Core Orchestrator ======================== -->
 
   <PropertyGroup>