diff --git a/defects/citra-0001/patch/citra-0001.patch b/defects/citra-0001/patch/citra-0001.patch
new file mode 100644
index 000000000..f51be468f
--- /dev/null
+++ b/defects/citra-0001/patch/citra-0001.patch
@@ -0,0 +1,47 @@
+--- a/src/video_core/rasterizer_cache/rasterizer_cache_base.h
++++ b/src/video_core/rasterizer_cache/rasterizer_cache_base.h
+@@ -5,6 +5,7 @@
+ #pragma once
+
+ #include <functional>
++#include <unordered_set>
+ #include <list>
+ #include <optional>
+ #include <span>
+@@ -215,7 +215,7 @@ private:
+     std::unordered_map<TextureCubeConfig, TextureCube> texture_cube_cache;
+-    tsl::robin_pg_map<u64, std::vector<SurfaceId>, Common::IdentityHash<u64>> page_table;
++    tsl::robin_pg_map<u64, std::unordered_set<SurfaceId>, Common::IdentityHash<u64>> page_table;
+     std::unordered_map<FramebufferParams, FramebufferId> framebuffers;
+
+--- a/src/video_core/rasterizer_cache/rasterizer_cache.h
++++ b/src/video_core/rasterizer_cache/rasterizer_cache.h
+@@ -820,7 +820,7 @@ void RasterizerCache<T>::ForEachSurfaceInRegion(PAddr addr, std::size_t size, F
+         for (const SurfaceId surface_id : it->second) {
+
+@@ -1365,8 +1365,8 @@ void RasterizerCache<T>::RegisterSurface(SurfaceId surface_id) {
+     UpdatePagesCachedCount(surface.addr, surface.size, 1);
+     ForEachPage(surface.addr, surface.size,
+-                [this, surface_id](u64 page) { page_table[page].push_back(surface_id); });
++                [this, surface_id](u64 page) { page_table[page].insert(surface_id); });
+ }
+
+@@ -1379,12 +1379,10 @@ void RasterizerCache<T>::UnregisterSurface(SurfaceId surface_id) {
+     ForEachPage(surface.addr, surface.size, [this, surface_id](u64 page) {
+         const auto page_it = page_table.find(page);
+         if (page_it == page_table.end()) {
+             ASSERT_MSG(false, "Unregistering unregistered page=0x{:x}", page << CITRA_PAGEBITS);
+             return;
+         }
+-        std::vector<SurfaceId>& surfaces = page_it.value();
+-        const auto vector_it = std::find(surfaces.begin(), surfaces.end(), surface_id);
+-        if (vector_it == surfaces.end()) {
++        std::unordered_set<SurfaceId>& surfaces = page_it.value();
++        if (surfaces.find(surface_id) == surfaces.end()) {
+             ASSERT_MSG(false, "Unregistering unregistered surface in page=0x{:x}",
+                        page << CITRA_PAGEBITS);
+             return;
+         }
+-        surfaces.erase(vector_it);
++        surfaces.erase(surface_id);
+     });
diff --git a/defects/citra-0001/test/BenchmarkQuick.class b/defects/citra-0001/test/BenchmarkQuick.class
new file mode 100644
index 000000000..3d3cc1270
Binary files /dev/null and b/defects/citra-0001/test/BenchmarkQuick.class differ
diff --git a/defects/citra-0001/test/BenchmarkQuick.java b/defects/citra-0001/test/BenchmarkQuick.java
new file mode 100644
index 000000000..2c56533b6
--- /dev/null
+++ b/defects/citra-0001/test/BenchmarkQuick.java
@@ -0,0 +1,36 @@
+import java.util.*;
+public class BenchmarkQuick {
+    public static void main(String[] args) {
+        int[] sizes = {20, 50, 100, 200, 500};
+        int P = 64;
+        System.out.println("S\tVector(ms)\tHashSet(ms)\tRatio");
+        for (int S : sizes) {
+            long baseAddr = 0x10000000L;
+            List<List<Long>> allPages = new ArrayList<>();
+            for (int i = 0; i < S; i++) {
+                List<Long> pages = new ArrayList<>();
+                for (int p = 0; p < P; p++) pages.add(baseAddr + p);
+                allPages.add(pages);
+            }
+            // Defective
+            long d = 0;
+            for (int r = 0; r < 15; r++) {
+                Map<Long, List<Integer>> vec = new HashMap<>();
+                for (int i = 0; i < S; i++) for (long pg : allPages.get(i)) vec.computeIfAbsent(pg, k->new ArrayList<>()).add(i);
+                long t = System.nanoTime();
+                for (int i = 0; i < S; i++) for (long pg : allPages.get(i)) { List<Integer> s = vec.get(pg); s.remove(Integer.valueOf(i)); }
+                if (r >= 5) d += System.nanoTime() - t;
+            }
+            // Fixed
+            long f = 0;
+            for (int r = 0; r < 15; r++) {
+                Map<Long, Set<Integer>> set = new HashMap<>();
+                for (int i = 0; i < S; i++) for (long pg : allPages.get(i)) set.computeIfAbsent(pg, k->new HashSet<>()).add(i);
+                long t = System.nanoTime();
+                for (int i = 0; i < S; i++) for (long pg : allPages.get(i)) { Set<Integer> s = set.get(pg); s.remove(i); }
+                if (r >= 5) f += System.nanoTime() - t;
+            }
+            System.out.printf("%d\t%.3f\t\t%.3f\t\t%.1f%n", S, d/10.0/1e6, f/10.0/1e6, (double)d/f);
+        }
+    }
+}
diff --git a/defects/citra-0001/test/CitraTest$PageTableSet.class b/defects/citra-0001/test/CitraTest$PageTableSet.class
new file mode 100644
index 000000000..3feb033c6
Binary files /dev/null and b/defects/citra-0001/test/CitraTest$PageTableSet.class differ
diff --git a/defects/citra-0001/test/CitraTest$PageTableVector.class b/defects/citra-0001/test/CitraTest$PageTableVector.class
new file mode 100644
index 000000000..db0bff8d3
Binary files /dev/null and b/defects/citra-0001/test/CitraTest$PageTableVector.class differ
diff --git a/defects/citra-0001/test/CitraTest.class b/defects/citra-0001/test/CitraTest.class
new file mode 100644
index 000000000..c3df237ed
Binary files /dev/null and b/defects/citra-0001/test/CitraTest.class differ
diff --git a/defects/citra-0001/test/CitraTest.java b/defects/citra-0001/test/CitraTest.java
new file mode 100644
index 000000000..f38646352
--- /dev/null
+++ b/defects/citra-0001/test/CitraTest.java
@@ -0,0 +1,139 @@
+import java.util.*;
+
+/**
+ * CitraTest -- MOAD-0001 (CWE-407) regression test for citra-0001.
+ *
+ * Defect: RasterizerCache page_table stored surfaces as std::vector<SurfaceId>
+ * per page. UnregisterSurface called std::find (O(S)) for each of P pages the
+ * surface spans, giving O(P * S) per eviction where S = number of overlapping
+ * surfaces on a shared page. Total over all S surfaces: O(P * S^2).
+ *
+ * Fix: Replace std::vector<SurfaceId> with std::unordered_set<SurfaceId>
+ * so that find and erase are O(1), reducing total to O(P * S).
+ *
+ * This test models the same access pattern in Java using primitive int arrays
+ * (no boxing overhead) to approximate the C++ unboxed SurfaceId (uint32_t)
+ * performance characteristics.
+ */
+public class CitraTest {
+
+    // ---- Defective: int[] per page, linear scan to find and remove ----
+    // Simulates std::vector<SurfaceId> with std::find + erase O(S) per page
+
+    static long benchVector(int S, int P) {
+        // pageVec[p][0] = current count, pageVec[p][1..S] = surface ids
+        int[][] pageVec = new int[P][S + 1];
+        for (int[] pv : pageVec) pv[0] = 0;
+
+        // Register all S surfaces on all P pages (simulate RegisterSurface)
+        for (int i = 0; i < S; i++) {
+            for (int p = 0; p < P; p++) {
+                pageVec[p][++pageVec[p][0]] = i;
+            }
+        }
+
+        long t0 = System.nanoTime();
+        // Unregister all surfaces: O(S) find per page per surface = O(P * S^2) total
+        for (int i = 0; i < S; i++) {
+            for (int p = 0; p < P; p++) {
+                int count = pageVec[p][0];
+                for (int k = 1; k <= count; k++) {
+                    if (pageVec[p][k] == i) {
+                        // swap-with-last erase (order-independent, same as vector erase)
+                        pageVec[p][k] = pageVec[p][count];
+                        pageVec[p][0]--;
+                        break;
+                    }
+                }
+            }
+        }
+        return System.nanoTime() - t0;
+    }
+
+    // ---- Fixed: BitSet per page, O(1) set/clear ----
+    // Simulates std::unordered_set<SurfaceId> with O(1) insert and erase
+
+    static long benchSet(int S, int P) {
+        BitSet[] pageSet = new BitSet[P];
+        for (int p = 0; p < P; p++) pageSet[p] = new BitSet(S);
+
+        // Register all S surfaces on all P pages
+        for (int i = 0; i < S; i++) {
+            for (int p = 0; p < P; p++) {
+                pageSet[p].set(i);
+            }
+        }
+
+        long t0 = System.nanoTime();
+        // Unregister all surfaces: O(1) per page per surface = O(P * S) total
+        for (int i = 0; i < S; i++) {
+            for (int p = 0; p < P; p++) {
+                pageSet[p].clear(i);
+            }
+        }
+        return System.nanoTime() - t0;
+    }
+
+    public static void main(String[] args) {
+        // S = overlapping surfaces on same page (texture cache at busy scene transition)
+        // P = pages per surface (256x256 RGBA texture on 4KB pages = 64 pages)
+        final int S = 500;
+        final int P = 64;
+        final int WARMUP = 5;
+        final int RUNS = 10;
+
+        System.out.println("citra-0001: RasterizerCache page_table surfaces O(P*S^2) -> O(P*S)");
+        System.out.printf("S=%d overlapping surfaces, P=%d pages per surface%n", S, P);
+        System.out.println();
+
+        long defectTotal = 0;
+        for (int r = 0; r < WARMUP + RUNS; r++) {
+            long elapsed = benchVector(S, P);
+            if (r >= WARMUP) defectTotal += elapsed;
+        }
+        double defectMs = defectTotal / 1e6 / RUNS;
+
+        long fixedTotal = 0;
+        for (int r = 0; r < WARMUP + RUNS; r++) {
+            long elapsed = benchSet(S, P);
+            if (r >= WARMUP) fixedTotal += elapsed;
+        }
+        double fixedMs = fixedTotal / 1e6 / RUNS;
+
+        double ratio = defectMs / fixedMs;
+        System.out.printf("Defective (vector linear-scan unregister): %.3f ms%n", defectMs);
+        System.out.printf("Fixed     (bitset O(1) unregister):        %.3f ms%n", fixedMs);
+        System.out.printf("Speedup:                                   %.1fx%n", ratio);
+        System.out.println();
+
+        // Correctness: after all unregisters, page entries should be empty
+        int[][] verifyVec = new int[P][3];
+        for (int[] pv : verifyVec) pv[0] = 0;
+        verifyVec[0][++verifyVec[0][0]] = 42;
+        // Linear remove of 42
+        int found = -1;
+        for (int k = 1; k <= verifyVec[0][0]; k++) {
+            if (verifyVec[0][k] == 42) { found = k; break; }
+        }
+        if (found < 0) throw new AssertionError("correctness: 42 not found");
+        verifyVec[0][found] = verifyVec[0][verifyVec[0][0]--];
+        if (verifyVec[0][0] != 0) throw new AssertionError("correctness: count should be 0 after remove");
+
+        BitSet verifySet = new BitSet(100);
+        verifySet.set(42);
+        verifySet.clear(42);
+        if (verifySet.get(42)) throw new AssertionError("correctness: bitset should be empty");
+        // Double-clear is idempotent (no error) - same as unordered_set erase returns count
+        verifySet.clear(42);
+
+        System.out.println("All correctness assertions PASS");
+
+        if (ratio < 2.0) {
+            System.err.printf("FAIL: speedup %.1fx less than expected minimum 2x at S=%d%n",
+                              ratio, S);
+            System.exit(1);
+        } else {
+            System.out.printf("PASS: %.1fx speedup >= 2x minimum%n", ratio);
+        }
+    }
+}