diff --git a/queries/undeclared-action-input.ql b/queries/undeclared-action-input.ql
new file mode 100644
index 000000000..a8ec7c3f4
--- /dev/null
+++ b/queries/undeclared-action-input.ql
@@ -0,0 +1,65 @@
+/**
+ * @name Undeclared action input
+ * @description Code tries to use an input parameter that is not defined for this action.
+   Perhaps this code is shared by multiple actions.
+ * @kind problem
+ * @problem.severity error
+ * @id javascript/codeql-action/undeclared-action-input
+ */
+
+import javascript
+
+class ActionDeclaration extends File {
+  ActionDeclaration() {
+    getRelativePath().matches("%/action.yml")
+  }
+
+  string getName() {
+    result = getRelativePath().regexpCapture("(.*)/action.yml", 1)
+  }
+
+  YAMLDocument getRootNode() {
+    result.getFile() = this
+  }
+
+  string getAnInput() {
+    result = getRootNode().(YAMLMapping).lookup("inputs").(YAMLMapping).getKey(_).(YAMLString).getValue()
+  }
+
+  FunctionDeclStmt getEntrypoint() {
+    result.getFile().getRelativePath() = getRootNode().
+      (YAMLMapping).lookup("runs").
+      (YAMLMapping).lookup("main").
+      (YAMLString).getValue().regexpReplaceAll("\\.\\./lib/(.*)\\.js", "src/$1.ts") and
+    result.getName() = "run"
+  }
+}
+
+Expr getAFunctionChildExpr(Function f) {
+  result.getContainer() = f
+}
+
+/*
+ * Result is a function that is called from the body of the given function `f`
+ */
+Function calledBy(Function f) {
+  result = getAFunctionChildExpr(f).(InvokeExpr).getResolvedCallee()
+  or
+  result.getEnclosingContainer() = f // assume outer function causes inner function to be called
+}
+
+class GetInputMethodCallExpr extends MethodCallExpr {
+  GetInputMethodCallExpr() {
+    getMethodName() = "getInput"
+  }
+
+  string getInputName() {
+    result = getArgument(0).(StringLiteral).getValue()
+  }
+}
+
+from ActionDeclaration action, GetInputMethodCallExpr getInputCall, string inputName
+where getAFunctionChildExpr(calledBy*(action.getEntrypoint())) = getInputCall and
+  inputName = getInputCall.getInputName() and
+  not inputName = action.getAnInput()
+select getInputCall, "The $@ input is not defined for the $@ action", inputName, inputName, action, action.getName()