@@ -38,6 +38,15 @@ changes:
     description: This feature is no longer experimental.
 -->
 
+<!-- worker-execargv-permission-ceiling -->
+When the Permission Model is enabled in the parent process, creating a
+`worker_threads.Worker` with an explicit `execArgv` option (including an empty
+array) no longer allows the worker to obtain a wider permission-related grant
+set than the parent. Non-permission `execArgv` flags are unaffected. This is a
+breaking change relative to earlier releases where `execArgv: []` could drop
+the parent's Permission Model grants.
+
+
 > Stability: 2 - Stable
 
 The Node.js Permission Model is a mechanism for restricting access to specific
 
@@ -1605,6 +1605,13 @@ changes:
     description: The `resourceLimits` option was introduced.
 -->
 
+<!-- worker-execargv-permission-ceiling -->
+**Permission Model (breaking):** If the parent process runs with the
+Permission Model enabled, an explicit `execArgv` (including `[]`) does not
+disable or exceed the parent's permission-related grants. See the
+[Permission Model](permissions.md#permission-model) documentation.
+
+
 * `filename` {string|URL} The path to the Worker's main script or module. Must
   be either an absolute path or a relative path (i.e. relative to the
   current working directory) starting with `./` or `../`, or a WHATWG `URL`
 
@@ -11,6 +11,7 @@
 #include "node_profiling.h"
 #include "node_snapshot_builder.h"
 #include "permission/permission.h"
+#include "path.h"
 #include "util-inl.h"
 #include "v8-cppgc.h"
 #include "v8-profiler.h"
@@ -504,6 +505,253 @@ Worker::~Worker() {
   Debug(this, "Worker %llu destroyed", thread_id_.id);
 }
 
+
+// SEMVER-MAJOR: Permission ceiling for Worker explicit execArgv.
+static bool WorkerConfiguredPermission(const EnvironmentOptions* w) {
+  if (w->permission || w->permission_audit) {
+    return true;
+  }
+  if (!w->allow_fs_read.empty() || !w->allow_fs_write.empty()) {
+    return true;
+  }
+  return w->allow_addons || w->allow_inspector || w->allow_child_process ||
+         w->allow_net || w->allow_wasi || w->allow_ffi ||
+         w->allow_openssl_store || w->allow_worker_threads;
+}
+
+static void ApplyParentPermissionCeiling(EnvironmentOptions* w,
+                                         const EnvironmentOptions* parent) {
+  w->permission = true;
+  w->permission_audit = parent->permission_audit;
+  w->allow_addons = parent->allow_addons;
+  w->allow_inspector = parent->allow_inspector;
+  w->allow_child_process = parent->allow_child_process;
+  w->allow_net = parent->allow_net;
+  w->allow_wasi = parent->allow_wasi;
+  w->allow_ffi = parent->allow_ffi;
+  w->allow_openssl_store = parent->allow_openssl_store;
+  w->allow_worker_threads = parent->allow_worker_threads;
+  w->allow_fs_read = parent->allow_fs_read;
+  w->allow_fs_write = parent->allow_fs_write;
+}
+
+static void NormalizePathForCompare(std::string* s) {
+  while (s->size() > 1 && (s->back() == '/' || s->back() == '\\')) {
+    s->pop_back();
+  }
+#ifdef _WIN32
+  for (char& c : *s) {
+    if (c >= 'A' && c <= 'Z') {
+      c = static_cast<char>(c - 'A' + 'a');
+    }
+    if (c == '/') {
+      c = '\\';
+    }
+  }
+#endif
+}
+
+static std::string ResolveForCompare(Environment* env, const std::string& in) {
+  if (in.empty() || in == "*") {
+    return in;
+  }
+  std::string resolved =
+      PathResolve(env, std::vector<std::string_view>{std::string_view(in)});
+  if (resolved.empty()) {
+    resolved = in;
+  }
+  NormalizePathForCompare(&resolved);
+  return resolved;
+}
+
+static bool PathCoveredByParentEntry(Environment* env,
+                                     const std::string& parent_raw,
+                                     const std::string& requested_raw) {
+  if (parent_raw == "*") {
+    return true;
+  }
+  const std::string parent = ResolveForCompare(env, parent_raw);
+  const std::string requested = ResolveForCompare(env, requested_raw);
+  if (parent.empty()) {
+    return false;
+  }
+  if (requested == parent) {
+    return true;
+  }
+  if (requested.size() <= parent.size()) {
+    return false;
+  }
+  if (requested.compare(0, parent.size(), parent) != 0) {
+    return false;
+  }
+  const char next = requested[parent.size()];
+  return next == '/' || next == '\\';
+}
+
+static bool ParentListHasWildcard(const std::vector<std::string>& parent) {
+  for (const std::string& entry : parent) {
+    if (entry == "*") {
+      return true;
+    }
+  }
+  return false;
+}
+
+static void FilterPathListToParentSubset(
+    Environment* env,
+    EnvironmentOptions* w,
+    std::vector<std::string>* worker,
+    const std::vector<std::string>& parent) {
+  if (worker == nullptr) {
+    return;
+  }
+  if (worker->empty()) {
+    if (w->permission || w->permission_audit) {
+      return;
+    }
+    *worker = parent;
+    return;
+  }
+  if (ParentListHasWildcard(parent)) {
+    return;
+  }
+  std::vector<std::string> out;
+  out.reserve(worker->size());
+  for (const std::string& wpath : *worker) {
+    if (wpath == "*") {
+      continue;
+    }
+    for (const std::string& entry : parent) {
+      if (PathCoveredByParentEntry(env, entry, wpath)) {
+        out.push_back(wpath);
+        break;
+      }
+    }
+  }
+  *worker = std::move(out);
+}
+
+static void IntersectPermissionGrants(Environment* env,
+                                      EnvironmentOptions* w,
+                                      const EnvironmentOptions* parent) {
+  w->permission = true;
+  w->permission_audit = w->permission_audit || parent->permission_audit;
+  w->allow_addons = w->allow_addons && parent->allow_addons;
+  w->allow_inspector = w->allow_inspector && parent->allow_inspector;
+  w->allow_child_process =
+      w->allow_child_process && parent->allow_child_process;
+  w->allow_net = w->allow_net && parent->allow_net;
+  w->allow_wasi = w->allow_wasi && parent->allow_wasi;
+  w->allow_ffi = w->allow_ffi && parent->allow_ffi;
+  w->allow_openssl_store =
+      w->allow_openssl_store && parent->allow_openssl_store;
+  w->allow_worker_threads =
+      w->allow_worker_threads && parent->allow_worker_threads;
+  FilterPathListToParentSubset(env, w, &w->allow_fs_read, parent->allow_fs_read);
+  FilterPathListToParentSubset(
+      env, w, &w->allow_fs_write, parent->allow_fs_write);
+}
+
+static void ClampWorkerPermissionToParent(Environment* env,
+                                          PerIsolateOptions* worker_opts) {
+  if (worker_opts == nullptr || !env->permission()->enabled()) {
+    return;
+  }
+  EnvironmentOptions* parent = env->isolate_data()->options()->get_per_env_options();
+  EnvironmentOptions* w = worker_opts->get_per_env_options();
+  if (parent == nullptr || w == nullptr) {
+    return;
+  }
+  if (!WorkerConfiguredPermission(w)) {
+    ApplyParentPermissionCeiling(w, parent);
+  } else {
+    IntersectPermissionGrants(env, w, parent);
+  }
+}
+
+static bool IsPermissionCliToken(const std::string& a) {
+  if (a == "--permission" || a == "--permission-audit") {
+    return true;
+  }
+  static const char* kFlags[] = {
+      "--allow-fs-read",
+      "--allow-fs-write",
+      "--allow-addons",
+      "--allow-inspector",
+      "--allow-child-process",
+      "--allow-net",
+      "--allow-wasi",
+      "--allow-ffi",
+      "--allow-openssl-store",
+      "--allow-worker",
+  };
+  for (const char* flag : kFlags) {
+    const size_t n = std::char_traits<char>::length(flag);
+    if (a == flag) {
+      return true;
+    }
+    if (a.size() > n && a.compare(0, n, flag) == 0 && a[n] == '=') {
+      return true;
+    }
+  }
+  return false;
+}
+
+static void RebuildExecArgvOutFromPermissionOptions(
+    PerIsolateOptions* worker_opts, std::vector<std::string>* exec_argv_out) {
+  if (worker_opts == nullptr || exec_argv_out == nullptr) {
+    return;
+  }
+  EnvironmentOptions* w = worker_opts->get_per_env_options();
+  if (w == nullptr || !w->permission) {
+    return;
+  }
+
+  std::vector<std::string> out;
+  out.emplace_back("");
+  for (size_t i = 1; i < exec_argv_out->size(); i++) {
+    if (!IsPermissionCliToken((*exec_argv_out)[i])) {
+      out.push_back((*exec_argv_out)[i]);
+    }
+  }
+  out.push_back("--permission");
+  if (w->permission_audit) {
+    out.push_back("--permission-audit");
+  }
+  if (w->allow_addons) {
+    out.push_back("--allow-addons");
+  }
+  if (w->allow_inspector) {
+    out.push_back("--allow-inspector");
+  }
+  if (w->allow_child_process) {
+    out.push_back("--allow-child-process");
+  }
+  if (w->allow_net) {
+    out.push_back("--allow-net");
+  }
+  if (w->allow_wasi) {
+    out.push_back("--allow-wasi");
+  }
+  if (w->allow_ffi) {
+    out.push_back("--allow-ffi");
+  }
+  if (w->allow_openssl_store) {
+    out.push_back("--allow-openssl-store");
+  }
+  if (w->allow_worker_threads) {
+    out.push_back("--allow-worker");
+  }
+  for (const std::string& path : w->allow_fs_read) {
+    out.push_back("--allow-fs-read=" + path);
+  }
+  for (const std::string& path : w->allow_fs_write) {
+    out.push_back("--allow-fs-write=" + path);
+  }
+  *exec_argv_out = std::move(out);
+}
+
+
 void Worker::New(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   THROW_IF_INSUFFICIENT_PERMISSIONS(
@@ -683,6 +931,14 @@ void Worker::New(const FunctionCallbackInfo<Value>& args) {
     per_isolate_opts = env->isolate_data()->options()->Clone();
   }
 
+  // Explicit execArgv (including []): clamp grants and rebuild argv so
+  // CreateEnvironment enables Permission with the parent ceiling.
+  if (env->permission()->enabled() && per_isolate_opts && args[2]->IsArray()) {
+    ClampWorkerPermissionToParent(env, per_isolate_opts.get());
+    RebuildExecArgvOutFromPermissionOptions(per_isolate_opts.get(),
+                                            &exec_argv_out);
+  }
+
   // Internal workers should not wait for inspector frontend to connect or
   // break on the first line of internal scripts. Module loader threads are
   // essential to load user codes and must not be blocked by the inspector