diff --git a/CHANGELOG.md b/CHANGELOG.md
index a861ec00c9..3f3c7839dd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,8 @@ You can also check the
     component for smaller breakpoints
 - Maintenance
   - Improved code organization around Browse page
+- Security
+  - Improved security of color palette API routes
 
 ### 6.0.0 - 2025-09-05
 
diff --git a/app/db/palettes.ts b/app/db/palettes.ts
index 57e5c22519..780dab5058 100644
--- a/app/db/palettes.ts
+++ b/app/db/palettes.ts
@@ -10,7 +10,7 @@ import {
 } from "@/utils/chart-config/api";
 
 export const createPaletteForUser = async (
-  data: CreateCustomColorPalette & { user_id?: number }
+  data: CreateCustomColorPalette & { user_id: number }
 ): Promise<CustomPaletteType> => {
   const palette = await prisma.palette.create({
     data: {
@@ -28,9 +28,11 @@ export const createPaletteForUser = async (
   };
 };
 
-export const getPalettesForUser = async (
-  user_id?: number
-): Promise<CustomPaletteType[]> => {
+export const getPalettesForUser = async ({
+  user_id,
+}: {
+  user_id: number;
+}): Promise<CustomPaletteType[]> => {
   const palettes = await prisma.palette.findMany({
     where: {
       user_id,
@@ -47,7 +49,23 @@ export const getPalettesForUser = async (
   });
 };
 
-export const deletePaletteForUser = async (paletteId: string) => {
+export const deletePaletteForUser = async ({
+  paletteId,
+  user_id,
+}: {
+  paletteId: string;
+  user_id: number;
+}) => {
+  const palette = await prisma.palette.findUnique({
+    where: {
+      paletteId,
+    },
+  });
+
+  if (!palette || palette.user_id !== user_id) {
+    throw new Error("Palette not found");
+  }
+
   await prisma.palette.delete({
     where: {
       paletteId,
@@ -55,17 +73,31 @@ export const deletePaletteForUser = async (paletteId: string) => {
   });
 };
 
-export const updatePaletteForUser = async (data: UpdateCustomColorPalette) => {
-  const type = data.type && convertPaletteTypeToDBType(data.type);
+export const updatePaletteForUser = async ({
+  type,
+  paletteId,
+  name,
+  colors,
+  user_id,
+}: UpdateCustomColorPalette & { user_id: number }) => {
+  const palette = await prisma.palette.findUnique({
+    where: {
+      paletteId,
+    },
+  });
+
+  if (!palette || palette.user_id !== user_id) {
+    throw new Error("Palette not found");
+  }
 
   await prisma.palette.update({
     where: {
-      paletteId: data.paletteId,
+      paletteId,
     },
     data: {
-      name: data.name,
-      colors: data.colors,
-      type,
+      name,
+      colors,
+      type: type && convertPaletteTypeToDBType(type),
       updated_at: new Date(),
     },
   });
diff --git a/app/prisma/schema.prisma b/app/prisma/schema.prisma
index be1f7764e3..853f8e544c 100644
--- a/app/prisma/schema.prisma
+++ b/app/prisma/schema.prisma
@@ -75,7 +75,7 @@ model Palette {
   created_at DateTime     @default(now()) @db.Timestamp(6)
   updated_at DateTime     @default(now()) @db.Timestamp(6)
   
-  user       User?        @relation(fields: [user_id], references: [id])
+  user       User?         @relation(fields: [user_id], references: [id], onDelete: Cascade)
   user_id    Int?
 
   @@map("palettes")
diff --git a/app/server/user-controller.ts b/app/server/user-controller.ts
index 62962cddbb..9062afb52d 100644
--- a/app/server/user-controller.ts
+++ b/app/server/user-controller.ts
@@ -18,6 +18,13 @@ export const UserController = controller({
   createPalette: async ({ req, res }) => {
     const session = await getServerSession(req, res, nextAuthOptions);
     const userId = session?.user?.id;
+
+    if (!userId) {
+      throw new Error(
+        "You must be logged in to create a custom color palette!"
+      );
+    }
+
     const data: CreateCustomColorPalette = req.body;
 
     return await createPaletteForUser({
@@ -29,18 +36,41 @@ export const UserController = controller({
     const session = await getServerSession(req, res, nextAuthOptions);
     const userId = session?.user?.id;
 
-    return await getPalettesForUser(userId);
+    if (!userId) {
+      throw new Error(
+        "You must be logged in to view your custom color palettes!"
+      );
+    }
+
+    return await getPalettesForUser({ user_id: userId });
   },
-  deletePalette: async ({ req }) => {
+  deletePalette: async ({ req, res }) => {
+    const session = await getServerSession(req, res, nextAuthOptions);
+    const userId = session?.user?.id;
+
+    if (!userId) {
+      throw new Error(
+        "You must be logged in to delete a custom color palette!"
+      );
+    }
+
     const data: DeleteCustomColorPalette = req.body;
-    const paletteId = data.paletteId;
 
-    await deletePaletteForUser(paletteId);
+    await deletePaletteForUser({ ...data, user_id: userId });
   },
 
-  updatePalette: async ({ req }) => {
+  updatePalette: async ({ req, res }) => {
+    const session = await getServerSession(req, res, nextAuthOptions);
+    const userId = session?.user?.id;
+
+    if (!userId) {
+      throw new Error(
+        "You must be logged in to update a custom color palette!"
+      );
+    }
+
     const data: UpdateCustomColorPalette = req.body;
 
-    await updatePaletteForUser(data);
+    await updatePaletteForUser({ ...data, user_id: userId });
   },
 });
diff --git a/app/utils/chart-config/api.ts b/app/utils/chart-config/api.ts
index a3694d58ca..d724b9ffee 100644
--- a/app/utils/chart-config/api.ts
+++ b/app/utils/chart-config/api.ts
@@ -13,6 +13,7 @@ import { createId } from "../create-id";
 import type apiConfig from "../../pages/api/config/[key]";
 import type apiConfigCreate from "../../pages/api/config-create";
 import type apiConfigUpdate from "../../pages/api/config-update";
+import type apiUserColorPalette from "../../pages/api/user/color-palette";
 
 export type CreateCustomColorPalette = Omit<CustomPaletteType, "paletteId">;
 export type UpdateCustomColorPalette = Partial<
@@ -116,7 +117,7 @@ export const fetchChartViewCount = async (id: string) => {
 export const createCustomColorPalette = async (
   options: CreateCustomColorPalette
 ) => {
-  return (await apiFetch<InferAPIResponse<typeof apiConfigCreate, "POST">>(
+  return (await apiFetch<InferAPIResponse<typeof apiUserColorPalette, "POST">>(
     "/api/user/color-palette",
     {
       method: "POST",
@@ -128,7 +129,7 @@ export const createCustomColorPalette = async (
 export const getCustomColorPalettes = async (): Promise<
   CustomPaletteType[]
 > => {
-  return (await apiFetch<InferAPIResponse<typeof apiConfigCreate, "GET">>(
+  return (await apiFetch<InferAPIResponse<typeof apiUserColorPalette, "GET">>(
     "/api/user/color-palette",
     {
       method: "GET",
@@ -139,7 +140,7 @@ export const getCustomColorPalettes = async (): Promise<
 export const deleteCustomColorPalette = async (
   options: DeleteCustomColorPalette
 ) => {
-  await apiFetch<InferAPIResponse<typeof apiConfigCreate, "DELETE">>(
+  await apiFetch<InferAPIResponse<typeof apiUserColorPalette, "DELETE">>(
     "/api/user/color-palette",
     {
       method: "DELETE",
@@ -151,7 +152,7 @@ export const deleteCustomColorPalette = async (
 export const updateCustomColorPalette = async (
   options: UpdateCustomColorPalette
 ) => {
-  await apiFetch<InferAPIResponse<typeof apiConfigCreate, "PUT">>(
+  await apiFetch<InferAPIResponse<typeof apiUserColorPalette, "PUT">>(
     "/api/user/color-palette",
     {
       method: "PUT",