diff --git a/internal/oidc/callback/callback_handler.go b/internal/oidc/callback/callback_handler.go
index 5b725623..f237726b 100644
--- a/internal/oidc/callback/callback_handler.go
+++ b/internal/oidc/callback/callback_handler.go
@@ -5,10 +5,10 @@
 package callback
 
 import (
+	"crypto/subtle"
 	"fmt"
 	"net/http"
 	"net/url"
-	"path"
 	"time"
 
 	"github.com/ory/fosite"
@@ -49,7 +49,7 @@ func NewHandler(
 			return err
 		}
 
-		upstreamIDPConfig := findUpstreamIDPConfig(r, idpListGetter)
+		upstreamIDPConfig := findUpstreamIDPConfig(state.UpstreamName, idpListGetter)
 		if upstreamIDPConfig == nil {
 			plog.Warning("upstream provider not found")
 			return httperr.New(http.StatusUnprocessableEntity, "upstream provider not found")
@@ -137,7 +137,7 @@ func validateRequest(r *http.Request, stateDecoder, cookieDecoder oidc.Decoder)
 		return nil, err
 	}
 
-	if state.CSRFToken != csrfValue {
+	if subtle.ConstantTimeCompare([]byte(state.CSRFToken), []byte(csrfValue)) != 1 {
 		plog.InfoErr("CSRF value does not match", err)
 		return nil, httperr.Wrap(http.StatusForbidden, "CSRF value does not match", err)
 	}
@@ -145,10 +145,9 @@ func validateRequest(r *http.Request, stateDecoder, cookieDecoder oidc.Decoder)
 	return state, nil
 }
 
-func findUpstreamIDPConfig(r *http.Request, idpListGetter oidc.IDPListGetter) provider.UpstreamOIDCIdentityProviderI {
-	_, lastPathComponent := path.Split(r.URL.Path)
+func findUpstreamIDPConfig(upstreamName string, idpListGetter oidc.IDPListGetter) provider.UpstreamOIDCIdentityProviderI {
 	for _, p := range idpListGetter.GetIDPList() {
-		if p.GetName() == lastPathComponent {
+		if p.GetName() == upstreamName {
 			return p
 		}
 	}
diff --git a/internal/oidc/callback/callback_handler_test.go b/internal/oidc/callback/callback_handler_test.go
index 5f1d16ba..c51ad86a 100644
--- a/internal/oidc/callback/callback_handler_test.go
+++ b/internal/oidc/callback/callback_handler_test.go
@@ -6,7 +6,6 @@ package callback
 import (
 	"context"
 	"errors"
-	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -507,25 +506,18 @@ func TestCallbackEndpoint(t *testing.T) {
 }
 
 type requestPath struct {
-	upstreamIDPName, code, state *string
+	code, state *string
 }
 
 func newRequestPath() *requestPath {
-	n := happyUpstreamIDPName
 	c := happyUpstreamAuthcode
 	s := "4321"
 	return &requestPath{
-		upstreamIDPName: &n,
-		code:            &c,
-		state:           &s,
+		code:  &c,
+		state: &s,
 	}
 }
 
-func (r *requestPath) WithUpstreamIDPName(name string) *requestPath {
-	r.upstreamIDPName = &name
-	return r
-}
-
 func (r *requestPath) WithCode(code string) *requestPath {
 	r.code = &code
 	return r
@@ -547,7 +539,7 @@ func (r *requestPath) WithoutState() *requestPath {
 }
 
 func (r *requestPath) String() string {
-	path := fmt.Sprintf("/downstream-provider-name/callback/%s?", *r.upstreamIDPName)
+	path := "/downstream-provider-name/callback?"
 	params := url.Values{}
 	if r.code != nil {
 		params.Add("code", *r.code)
@@ -562,6 +554,7 @@ type upstreamStateParamBuilder oidctestutil.ExpectedUpstreamStateParamFormat
 
 func happyUpstreamStateParam() *upstreamStateParamBuilder {
 	return &upstreamStateParamBuilder{
+		U: happyUpstreamIDPName,
 		P: happyDownstreamRequestParams,
 		N: happyDownstreamNonce,
 		C: happyDownstreamCSRF,