diff --git a/cmd/kurl/main.go b/cmd/kurl/main.go
index 0b56c49..9da738a 100644
--- a/cmd/kurl/main.go
+++ b/cmd/kurl/main.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"math"
 	"os"
 	"strconv"
 	"strings"
@@ -498,6 +499,9 @@ func parseTimeout(value string) (time.Duration, error) {
 	}
 
 	if seconds, err := strconv.ParseFloat(value, 64); err == nil {
+		if math.IsNaN(seconds) || math.IsInf(seconds, 0) || seconds*float64(time.Second) >= float64(math.MaxInt64) {
+			return 0, fmt.Errorf("invalid timeout %q: must be finite and fit in a duration", value)
+		}
 		if seconds < 0 {
 			return 0, fmt.Errorf("invalid timeout %q: must not be negative", value)
 		}
diff --git a/cmd/kurl/timeout_range_test.go b/cmd/kurl/timeout_range_test.go
new file mode 100644
index 0000000..f5fcadd
--- /dev/null
+++ b/cmd/kurl/timeout_range_test.go
@@ -0,0 +1,21 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestTimeoutRejectsNonFiniteAndOverflowSeconds(t *testing.T) {
+	for _, value := range []string{"NaN", "Inf", "+Inf", "-Inf", "1e100", "9223372037", "9223372036.854776"} {
+		t.Run(value, func(t *testing.T) {
+			if got, err := parseTimeout(value); err == nil {
+				t.Fatalf("parseTimeout(%q) = %s without error", value, got)
+			}
+		})
+	}
+	for value, want := range map[string]time.Duration{"0": 0, "0.5": 500 * time.Millisecond, "30": 30 * time.Second, "9223372036": 9223372036 * time.Second, "500ms": 500 * time.Millisecond} {
+		if got, err := parseTimeout(value); err != nil || got != want {
+			t.Errorf("parseTimeout(%q) = %s, %v; want %s", value, got, err, want)
+		}
+	}
+}