diff --git a/internal/pkg/auth/user_login.go b/internal/pkg/auth/user_login.go
index 822b7daff..3a46bb9a4 100644
--- a/internal/pkg/auth/user_login.go
+++ b/internal/pkg/auth/user_login.go
@@ -340,8 +340,12 @@ func cleanup(server *http.Server) {
 	}()
 }
 
-func openBrowser(pageUrl string) error {
-	var err error
+func openBrowser(pageUrl string) (err error) {
+	err = utils.ValidateURLDomain(pageUrl)
+	if err != nil {
+		return err
+	}
+
 	switch runtime.GOOS {
 	case "freebsd", "linux":
 		// We need to use the windows way on WSL, otherwise we do not pass query
diff --git a/internal/pkg/auth/utils.go b/internal/pkg/auth/utils.go
index faf24b687..a1e7eaf77 100644
--- a/internal/pkg/auth/utils.go
+++ b/internal/pkg/auth/utils.go
@@ -98,12 +98,21 @@ func parseWellKnownConfiguration(httpClient apiClient, wellKnownConfigURL string
 	if wellKnownConfig.Issuer == "" {
 		return nil, fmt.Errorf("found no issuer")
 	}
+	if utils.ValidateURLDomain(wellKnownConfig.Issuer) != nil {
+		return nil, fmt.Errorf("issuer is invalid")
+	}
 	if wellKnownConfig.AuthorizationEndpoint == "" {
 		return nil, fmt.Errorf("found no authorization endpoint")
 	}
+	if utils.ValidateURLDomain(wellKnownConfig.AuthorizationEndpoint) != nil {
+		return nil, fmt.Errorf("authorization endpoint is invalid")
+	}
 	if wellKnownConfig.TokenEndpoint == "" {
 		return nil, fmt.Errorf("found no token endpoint")
 	}
+	if utils.ValidateURLDomain(wellKnownConfig.TokenEndpoint) != nil {
+		return nil, fmt.Errorf("token endpoint is invalid")
+	}
 
 	err = SetAuthField(IDP_TOKEN_ENDPOINT, wellKnownConfig.TokenEndpoint)
 	if err != nil {
diff --git a/internal/pkg/auth/utils_test.go b/internal/pkg/auth/utils_test.go
index 6fd67fc75..228a2c94c 100644
--- a/internal/pkg/auth/utils_test.go
+++ b/internal/pkg/auth/utils_test.go
@@ -133,12 +133,12 @@ func TestParseWellKnownConfig(t *testing.T) {
 		{
 			name:        "success",
 			getFails:    false,
-			getResponse: `{"issuer":"issuer","authorization_endpoint":"auth","token_endpoint":"token"}`,
+			getResponse: `{"issuer":"https://issuer.stackit.cloud/endpoint","authorization_endpoint":"https://auth.stackit.cloud/enpoint","token_endpoint":"https://token.stackit.cloud/endpoint"}`,
 			isValid:     true,
 			expected: &wellKnownConfig{
-				Issuer:                "issuer",
-				AuthorizationEndpoint: "auth",
-				TokenEndpoint:         "token",
+				Issuer:                "https://issuer.stackit.cloud/endpoint",
+				AuthorizationEndpoint: "https://auth.stackit.cloud/enpoint",
+				TokenEndpoint:         "https://token.stackit.cloud/endpoint",
 			},
 		},
 		{
@@ -158,21 +158,21 @@ func TestParseWellKnownConfig(t *testing.T) {
 		{
 			name:        "missing_issuer",
 			getFails:    true,
-			getResponse: `{"authorization_endpoint":"auth","token_endpoint":"token"}`,
+			getResponse: `{"authorization_endpoint":"https://auth.stackit.cloud/enpoint","token_endpoint":"https://token.stackit.cloud/endpoint"}`,
 			isValid:     false,
 			expected:    nil,
 		},
 		{
 			name:        "missing_authorization",
 			getFails:    true,
-			getResponse: `{"issuer":"issuer","token_endpoint":"token"}`,
+			getResponse: `{"issuer":"https://issuer.stackit.cloud/endpoint","token_endpoint":"https://token.stackit.cloud/endpoint"}`,
 			isValid:     false,
 			expected:    nil,
 		},
 		{
 			name:        "missing_token",
 			getFails:    true,
-			getResponse: `{"issuer":"issuer","authorization_endpoint":"auth"}`,
+			getResponse: `{"issuer":"https://issuer.stackit.cloud/endpoint","authorization_endpoint":"https://auth.stackit.cloud/enpoint"}`,
 			isValid:     false,
 			expected:    nil,
 		},
diff --git a/internal/pkg/utils/utils.go b/internal/pkg/utils/utils.go
index 0cb50a3d4..594f411d3 100644
--- a/internal/pkg/utils/utils.go
+++ b/internal/pkg/utils/utils.go
@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"net/url"
+	"slices"
 	"strings"
 	"time"
 
@@ -82,11 +83,19 @@ func ValidateURLDomain(value string) error {
 	if err != nil {
 		return fmt.Errorf("parse url: %w", err)
 	}
+
 	urlHost := urlStruct.Hostname()
 	if urlHost == "" {
 		return fmt.Errorf("bad url")
 	}
 
+	allowedSchemes := []string{
+		"https",
+	}
+	if !slices.Contains(allowedSchemes, urlStruct.Scheme) {
+		return fmt.Errorf("unsupported protocol: %s", urlStruct.Scheme)
+	}
+
 	allowedUrlDomain := viper.GetString(config.AllowedUrlDomainKey)
 
 	if !strings.HasSuffix(urlHost, allowedUrlDomain) {
diff --git a/internal/pkg/utils/utils_test.go b/internal/pkg/utils/utils_test.go
index 0b5a656af..03b270309 100644
--- a/internal/pkg/utils/utils_test.go
+++ b/internal/pkg/utils/utils_test.go
@@ -97,6 +97,21 @@ func TestValidateURLDomain(t *testing.T) {
 			input:   "",
 			isValid: false,
 		},
+		{
+			name:    "invalid protocol",
+			input:   "http://example.stackit.cloud",
+			isValid: false,
+		},
+		{
+			name:    "no protocol",
+			input:   "example.stackit.cloud",
+			isValid: false,
+		},
+		{
+			name:    "valid endpoint",
+			input:   "https://service-account.api.stackit.cloud/token",
+			isValid: true,
+		},
 	}
 
 	for _, tt := range tests {