diff --git a/integrations/api_admin_test.go b/integrations/api_admin_test.go
index 690edad757a6..b8dded9c116a 100644
--- a/integrations/api_admin_test.go
+++ b/integrations/api_admin_test.go
@@ -39,8 +39,8 @@ func TestAPIAdminCreateAndDeleteSSHKey(t *testing.T) {
 		OwnerID:     keyOwner.ID,
 	})
 
-	req = NewRequestf(t, "DELETE", "/api/v1/admin/users/%s/keys/%d?token="+token,
-		keyOwner.Name, newPublicKey.ID)
+	req = NewRequestf(t, "DELETE", "/api/v1/admin/users/%s/keys/%d?token=%s",
+		keyOwner.Name, newPublicKey.ID, token)
 	session.MakeRequest(t, req, http.StatusNoContent)
 	models.AssertNotExistsBean(t, &models.PublicKey{ID: newPublicKey.ID})
 }
@@ -51,7 +51,7 @@ func TestAPIAdminDeleteMissingSSHKey(t *testing.T) {
 	session := loginUser(t, "user1")
 
 	token := getTokenForLoggedInUser(t, session)
-	req := NewRequestf(t, "DELETE", "/api/v1/admin/users/user1/keys/%d?token="+token, models.NonexistentID)
+	req := NewRequestf(t, "DELETE", "/api/v1/admin/users/user1/keys/%d?token=%s", models.NonexistentID, token)
 	session.MakeRequest(t, req, http.StatusNotFound)
 }
 
@@ -73,8 +73,8 @@ func TestAPIAdminDeleteUnauthorizedKey(t *testing.T) {
 
 	session = loginUser(t, normalUsername)
 	token = getTokenForLoggedInUser(t, session)
-	req = NewRequestf(t, "DELETE", "/api/v1/admin/users/%s/keys/%d?token="+token,
-		adminUsername, newPublicKey.ID)
+	req = NewRequestf(t, "DELETE", "/api/v1/admin/users/%s/keys/%d?token=%s",
+		adminUsername, newPublicKey.ID, token)
 	session.MakeRequest(t, req, http.StatusForbidden)
 }
 
diff --git a/integrations/git_test.go b/integrations/git_test.go
index 7ac375dd029d..96d39e0519e7 100644
--- a/integrations/git_test.go
+++ b/integrations/git_test.go
@@ -143,7 +143,8 @@ func TestGit(t *testing.T) {
 
 			session := loginUser(t, "user1")
 			keyOwner := models.AssertExistsAndLoadBean(t, &models.User{Name: "user2"}).(*models.User)
-			urlStr := fmt.Sprintf("/api/v1/admin/users/%s/keys", keyOwner.Name)
+			token := getTokenForLoggedInUser(t, session)
+			urlStr := fmt.Sprintf("/api/v1/admin/users/%s/keys?token=%s", keyOwner.Name, token)
 
 			dataPubKey, err := ioutil.ReadFile(keyFile + ".pub")
 			assert.NoError(t, err)
diff --git a/modules/context/api.go b/modules/context/api.go
index 0bf4307726e8..6a9c792370f4 100644
--- a/modules/context/api.go
+++ b/modules/context/api.go
@@ -8,6 +8,8 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/go-macaron/csrf"
+
 	"code.gitea.io/git"
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/base"
@@ -97,6 +99,17 @@ func (ctx *APIContext) SetLinkHeader(total, pageSize int) {
 	}
 }
 
+// RequireCSRF requires a validated a CSRF token
+func (ctx *APIContext) RequireCSRF() {
+	headerToken := ctx.Req.Header.Get(ctx.csrf.GetHeaderName())
+	formValueToken := ctx.Req.FormValue(ctx.csrf.GetFormName())
+	if len(headerToken) > 0 || len(formValueToken) > 0 {
+		csrf.Validate(ctx.Context.Context, ctx.csrf)
+	} else {
+		ctx.Context.Error(401)
+	}
+}
+
 // APIContexter returns apicontext as macaron middleware
 func APIContexter() macaron.Handler {
 	return func(c *Context) {
diff --git a/public/js/index.js b/public/js/index.js
index fad531cc4991..9bde52f97d1e 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -2590,6 +2590,10 @@ function updateDeadline(deadlineString) {
         data: JSON.stringify({
             'due_date': realDeadline,
         }),
+        headers: {
+            'X-Csrf-Token': csrf,
+            'X-Remote': true,
+        },
         contentType: 'application/json',
         type: 'POST',
         success: function () {
diff --git a/routers/api/v1/api.go b/routers/api/v1/api.go
index 23a85759c2f5..fe54aa2a320b 100644
--- a/routers/api/v1/api.go
+++ b/routers/api/v1/api.go
@@ -174,11 +174,15 @@ func repoAssignment() macaron.Handler {
 
 // Contexter middleware already checks token for user sign in process.
 func reqToken() macaron.Handler {
-	return func(ctx *context.Context) {
-		if true != ctx.Data["IsApiToken"] {
-			ctx.Error(401)
+	return func(ctx *context.APIContext) {
+		if true == ctx.Data["IsApiToken"] {
+			return
+		}
+		if ctx.IsSigned {
+			ctx.RequireCSRF()
 			return
 		}
+		ctx.Context.Error(401)
 	}
 }
 
@@ -627,7 +631,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 					m.Post("/repos", bind(api.CreateRepoOption{}), admin.CreateRepo)
 				})
 			})
-		}, reqAdmin())
+		}, reqToken(), reqAdmin())
 
 		m.Group("/topics", func() {
 			m.Get("/search", repo.TopicSearch)