diff --git a/src/config/schema.test.ts b/src/config/schema.test.ts
index 2c1780c5c6f..2d420efd868 100644
--- a/src/config/schema.test.ts
+++ b/src/config/schema.test.ts
@@ -271,6 +271,31 @@ describe("config schema", () => {
     expect(lookupConfigSchema(baseSchema, "__proto__.polluted")).toBeNull();
   });
 
+  it("rejects overly deep lookup paths", () => {
+    const buildNestedObjectSchema = (segments: string[]) => {
+      const [head, ...rest] = segments;
+      if (!head) {
+        return { type: "string" };
+      }
+      return {
+        type: "object",
+        properties: {
+          [head]: buildNestedObjectSchema(rest),
+        },
+      };
+    };
+
+    const deepPathSegments = Array.from({ length: 33 }, (_, index) => `a${index}`);
+    const deepSchema = {
+      schema: buildNestedObjectSchema(deepPathSegments),
+      uiHints: {},
+      version: "test",
+      generatedAt: "test",
+    } as unknown as Parameters<typeof lookupConfigSchema>[0];
+
+    expect(lookupConfigSchema(deepSchema, deepPathSegments.join("."))).toBeNull();
+  });
+
   it("returns null for missing config schema paths", () => {
     expect(lookupConfigSchema(baseSchema, "gateway.notReal.path")).toBeNull();
   });
diff --git a/src/config/schema.ts b/src/config/schema.ts
index bd4dbbac9cd..83227a375d5 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -51,6 +51,7 @@ const LOOKUP_SCHEMA_BOOLEAN_KEYS = new Set([
   "readOnly",
   "writeOnly",
 ]);
+const MAX_LOOKUP_PATH_SEGMENTS = 32;
 
 function cloneSchema<T>(value: T): T {
   if (typeof structuredClone === "function") {
@@ -682,12 +683,16 @@ export function lookupConfigSchema(
   if (!normalizedPath) {
     return null;
   }
+  const parts = splitLookupPath(normalizedPath);
+  if (parts.length === 0 || parts.length > MAX_LOOKUP_PATH_SEGMENTS) {
+    return null;
+  }
 
   let current = asSchemaObject(response.schema);
   if (!current) {
     return null;
   }
-  for (const segment of splitLookupPath(normalizedPath)) {
+  for (const segment of parts) {
     const next = resolveLookupChildSchema(current, segment);
     if (!next) {
       return null;
diff --git a/src/gateway/protocol/schema/config.ts b/src/gateway/protocol/schema/config.ts
index d3701fe00a0..78159549255 100644
--- a/src/gateway/protocol/schema/config.ts
+++ b/src/gateway/protocol/schema/config.ts
@@ -1,7 +1,11 @@
 import { Type } from "@sinclair/typebox";
 import { NonEmptyString } from "./primitives.js";
 
-const NonWhitespaceString = Type.String({ minLength: 1, pattern: ".*\\S.*" });
+const ConfigSchemaLookupPathString = Type.String({
+  minLength: 1,
+  maxLength: 1024,
+  pattern: "^[A-Za-z0-9_.\\[\\]\\-*]+$",
+});
 
 export const ConfigGetParamsSchema = Type.Object({}, { additionalProperties: false });
 
@@ -31,7 +35,7 @@ export const ConfigSchemaParamsSchema = Type.Object({}, { additionalProperties:
 
 export const ConfigSchemaLookupParamsSchema = Type.Object(
   {
-    path: NonWhitespaceString,
+    path: ConfigSchemaLookupPathString,
   },
   { additionalProperties: false },
 );
diff --git a/src/gateway/server.config-patch.test.ts b/src/gateway/server.config-patch.test.ts
index ad0974d8e39..44daced1684 100644
--- a/src/gateway/server.config-patch.test.ts
+++ b/src/gateway/server.config-patch.test.ts
@@ -87,6 +87,24 @@ describe("gateway config methods", () => {
     expect(res.error?.message ?? "").toContain("invalid config.schema.lookup params");
   });
 
+  it("rejects config.schema.lookup when the path exceeds the protocol limit", async () => {
+    const res = await rpcReq<{ ok?: boolean }>(requireWs(), "config.schema.lookup", {
+      path: `gateway.${"a".repeat(1020)}`,
+    });
+
+    expect(res.ok).toBe(false);
+    expect(res.error?.message ?? "").toContain("invalid config.schema.lookup params");
+  });
+
+  it("rejects config.schema.lookup when the path contains invalid characters", async () => {
+    const res = await rpcReq<{ ok?: boolean }>(requireWs(), "config.schema.lookup", {
+      path: "gateway.auth\nspoof",
+    });
+
+    expect(res.ok).toBe(false);
+    expect(res.error?.message ?? "").toContain("invalid config.schema.lookup params");
+  });
+
   it("rejects prototype-chain config.schema.lookup paths without reflecting them", async () => {
     const res = await rpcReq<{ ok?: boolean }>(requireWs(), "config.schema.lookup", {
       path: "constructor",