diff --git a/CHANGELOG.md b/CHANGELOG.md
index f03ed638..f89f4c1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/), and this
 
 ## [Unreleased]
 
+### Fixed
+- Bounded the source-shell overlap scan used by grouped UV transfer so highly fragmented, attacker-controlled meshes cannot trigger an unbounded quadratic pre-transfer pass and stall the Unity Editor.
+
 ### Added
 - **`UvProgress` service** (`Editor/Framework/UvProgress.cs`) — central non-modal progress reporting. Routes status to `UnityEditor.Progress` (Background Tasks panel) plus an inline strip drawn at the bottom of the hub window. Supports nested scopes, phase labels, indeterminate/determinate fractions, cooperative cancellation via `UvProgress.CancelRequested` (`Volatile.Read`-backed `_cancelFlag` so background `Task.Run` work observes user-cancel reliably across the memory barrier), a thread-safe `ReportFromBackground` for `Task.Run` callers (with `Interlocked.Exchange`-guarded snapshot/clear so a racing writer can't lose an update; the `EditorApplication.update` pump is hooked once on assembly load from the main thread via `[InitializeOnLoadMethod]`), and a `Last` outcome shown while idle.
 - **Inline progress strip in `UvToolHub`** — sits at the bottom of the window as a status bar. Reserves fixed height unconditionally so toggling active state doesn't displace any layout. Shows title · phase · detail · elapsed in distinct columns with a Cancel button pinned to the right; while idle displays `✓ / ✗ Last-operation · 12.3s`. Marquee animation for indeterminate fractions; orange tint while cancelling.
diff --git a/Editor/GroupedShellTransfer.cs b/Editor/GroupedShellTransfer.cs
index 297ae1b9..be249a6d 100644
--- a/Editor/GroupedShellTransfer.cs
+++ b/Editor/GroupedShellTransfer.cs
@@ -21,6 +21,11 @@ namespace SashaRX.UnityMeshLab
 {
     public static class GroupedShellTransfer
     {
+        // Keep overlap detection bounded: FindOverlapGroups compares every shell pair.
+        // Typical production meshes stay well below this limit; pathological meshes
+        // fall back to the original fixed retry count instead of stalling the Editor.
+        const int kMaxShellsForOverlapScan = 512;
+
         // ─── Similarity Transform (4 params: a, b, tx, ty) ───
         public struct SimilarityTransform
         {
@@ -1180,12 +1185,21 @@ static TransferResult TransferCore(
                 : 0.001f;
             float kUv0BadThreshold = Mathf.Max(avgUv0Edge * avgUv0Edge, 0.001f);
 
-            // Adaptive kMaxRetries based on overlap group size
-            var overlapGroups = UvShellExtractor.FindOverlapGroups(srcShells);
+            // Adaptive kMaxRetries based on overlap group size. The overlap detector is
+            // quadratic, so never run it for attacker-controlled, highly fragmented meshes.
+            bool scanOverlapGroups = srcShells.Count <= kMaxShellsForOverlapScan;
+            var overlapGroups = scanOverlapGroups
+                ? UvShellExtractor.FindOverlapGroups(srcShells)
+                : new List<List<int>>();
             int maxOverlapGroupSize = 0;
             foreach (var group in overlapGroups)
                 maxOverlapGroupSize = Mathf.Max(maxOverlapGroupSize, group.Count);
-            int kMaxRetries = Mathf.Clamp(maxOverlapGroupSize + 2, 5, srcShells.Count);
+            int kMaxRetries = scanOverlapGroups
+                ? Mathf.Clamp(maxOverlapGroupSize + 2, 5, srcShells.Count)
+                : Mathf.Min(5, srcShells.Count);
+
+            if (!scanOverlapGroups)
+                UvtLog.Warn($"[GroupedTransfer] Skipping quadratic UV overlap scan for {srcShells.Count} source shells (limit {kMaxShellsForOverlapScan}).");
 
             // Build overlap group membership: srcShell → list of all group members
             var srcShellOverlapMembers = new List<int>[srcShells.Count];