diff --git a/extensions/lobster/src/lobster-tool.test.ts b/extensions/lobster/src/lobster-tool.test.ts
index 26fa37c451db..98ce06765cbd 100644
--- a/extensions/lobster/src/lobster-tool.test.ts
+++ b/extensions/lobster/src/lobster-tool.test.ts
@@ -114,6 +114,28 @@ describe("lobster plugin tool", () => {
     ).rejects.toThrow(/absolute path/);
   });
 
+  it("rejects lobsterPath that is not the lobster executable", async () => {
+    const tool = createLobsterTool(fakeApi());
+    await expect(
+      tool.execute("call2b", {
+        action: "run",
+        pipeline: "noop",
+        lobsterPath: "/bin/bash",
+      }),
+    ).rejects.toThrow(/lobster executable/);
+  });
+
+  it("rejects absolute cwd", async () => {
+    const tool = createLobsterTool(fakeApi());
+    await expect(
+      tool.execute("call2c", {
+        action: "run",
+        pipeline: "noop",
+        cwd: "/tmp",
+      }),
+    ).rejects.toThrow(/cwd must be a relative path/);
+  });
+
   it("rejects invalid JSON from lobster", async () => {
     const { binPath } = await writeFakeLobsterScript(
       `process.stdout.write("nope");\n`,
diff --git a/extensions/lobster/src/lobster-tool.ts b/extensions/lobster/src/lobster-tool.ts
index 5b8998fee48d..dac23197ddf8 100644
--- a/extensions/lobster/src/lobster-tool.ts
+++ b/extensions/lobster/src/lobster-tool.ts
@@ -1,5 +1,6 @@
 import { Type } from "@sinclair/typebox";
 import { spawn } from "node:child_process";
+import fs from "node:fs";
 import path from "node:path";
 
 import type { OpenClawPluginApi } from "../../../src/plugins/types.js";
@@ -23,12 +24,56 @@ type LobsterEnvelope =
 
 function resolveExecutablePath(lobsterPathRaw: string | undefined) {
   const lobsterPath = lobsterPathRaw?.trim() || "lobster";
-  if (lobsterPath !== "lobster" && !path.isAbsolute(lobsterPath)) {
-    throw new Error("lobsterPath must be an absolute path (or omit to use PATH)");
+
+  // SECURITY:
+  // Never allow arbitrary executables (e.g. /bin/bash). If the caller overrides
+  // the path, it must still be the lobster binary (by name) and be absolute.
+  if (lobsterPath !== "lobster") {
+    if (!path.isAbsolute(lobsterPath)) {
+      throw new Error("lobsterPath must be an absolute path (or omit to use PATH)");
+    }
+    const base = path.basename(lobsterPath).toLowerCase();
+    const allowed =
+      process.platform === "win32"
+        ? ["lobster.exe", "lobster.cmd", "lobster.bat"]
+        : ["lobster"];
+    if (!allowed.includes(base)) {
+      throw new Error("lobsterPath must point to the lobster executable");
+    }
+    try {
+      const stat = fs.statSync(lobsterPath);
+      if (!stat.isFile()) {
+        throw new Error("lobsterPath must point to a file");
+      }
+      if (process.platform !== "win32") {
+        fs.accessSync(lobsterPath, fs.constants.X_OK);
+      }
+    } catch (err) {
+      const msg = err instanceof Error ? err.message : String(err);
+      throw new Error(`lobsterPath is not executable: ${msg}`);
+    }
   }
+
   return lobsterPath;
 }
 
+function resolveCwd(cwdRaw: unknown): string {
+  if (typeof cwdRaw !== "string" || !cwdRaw.trim()) {
+    return process.cwd();
+  }
+  const cwd = cwdRaw.trim();
+  if (path.isAbsolute(cwd)) {
+    throw new Error("cwd must be a relative path");
+  }
+  const base = process.cwd();
+  const resolved = path.resolve(base, cwd);
+  const rel = path.relative(base, resolved);
+  if (rel.startsWith("..") || path.isAbsolute(rel)) {
+    throw new Error("cwd must stay within the gateway working directory");
+  }
+  return resolved;
+}
+
 function isWindowsSpawnEINVAL(err: unknown) {
   if (!err || typeof err !== "object") {
     return false;
@@ -182,8 +227,13 @@ export function createLobsterTool(api: OpenClawPluginApi) {
       argsJson: Type.Optional(Type.String()),
       token: Type.Optional(Type.String()),
       approve: Type.Optional(Type.Boolean()),
-      lobsterPath: Type.Optional(Type.String()),
-      cwd: Type.Optional(Type.String()),
+      lobsterPath: Type.Optional(Type.String({ description: "Absolute path to the lobster executable (optional)." })),
+      cwd: Type.Optional(
+        Type.String({
+          description:
+            "Relative working directory (optional). Must stay within the gateway working directory.",
+        }),
+      ),
       timeoutMs: Type.Optional(Type.Number()),
       maxStdoutBytes: Type.Optional(Type.Number()),
     }),
@@ -196,8 +246,7 @@ export function createLobsterTool(api: OpenClawPluginApi) {
       const execPath = resolveExecutablePath(
         typeof params.lobsterPath === "string" ? params.lobsterPath : undefined,
       );
-      const cwd =
-        typeof params.cwd === "string" && params.cwd.trim() ? params.cwd.trim() : process.cwd();
+      const cwd = resolveCwd(params.cwd);
       const timeoutMs = typeof params.timeoutMs === "number" ? params.timeoutMs : 20_000;
       const maxStdoutBytes =
         typeof params.maxStdoutBytes === "number" ? params.maxStdoutBytes : 512_000;