diff --git a/backend/controllers/authController.js b/backend/controllers/authController.js
index 15688ad..3699af5 100644
--- a/backend/controllers/authController.js
+++ b/backend/controllers/authController.js
@@ -72,9 +72,9 @@ class AuthController {
     }
 
     async oauthExchange(req, res) {
-        const { code, state } = req.body;
+        const { code, state, iss } = req.body;
         try {
-            const result = await oauthService.exchangeOAuthLogin({ code, state });
+            const result = await oauthService.exchangeOAuthLogin({ code, state, iss });
             res.status(200).json(result);
         } catch (error) {
             const knownErrors = new Set([
@@ -128,7 +128,7 @@ class AuthController {
 
     async oauthUserExchange(req, res) {
         const hashedUserId = req.headers.userid || req.query.userid;
-        const { code, state } = req.body;
+        const { code, state, iss } = req.body;
         try {
             const User = (await import('../models/community/user.js')).default;
             const user = await User.findOne({ where: { hashedId: hashedUserId } });
@@ -139,7 +139,8 @@ class AuthController {
             const result = await oauthService.exchangeOAuthLoginForUser({
                 userId: user.id,
                 code,
-                state
+                state,
+                iss
             });
             res.status(200).json(result);
         } catch (error) {
diff --git a/backend/services/oauthService.js b/backend/services/oauthService.js
index e1b70e2..9ae9af9 100644
--- a/backend/services/oauthService.js
+++ b/backend/services/oauthService.js
@@ -361,7 +361,7 @@ export const startOAuthLogin = async ({ providerSlug }) => {
     });
 };
 
-export const exchangeOAuthLogin = async ({ code, state }) => {
+export const exchangeOAuthLogin = async ({ code, state, iss }) => {
     if (!code || !state) {
         throw new Error('oauthcodemissing');
     }
@@ -380,6 +380,9 @@ export const exchangeOAuthLogin = async ({ code, state }) => {
     const callbackUrl = new URL(stateData.redirectUri);
     callbackUrl.searchParams.set('code', code);
     callbackUrl.searchParams.set('state', state);
+    if (iss) {
+        callbackUrl.searchParams.set('iss', iss);
+    }
 
     const tokens = await oidc.authorizationCodeGrant(configuration, callbackUrl, {
         pkceCodeVerifier: stateData.codeVerifier,
@@ -494,7 +497,7 @@ export const startOAuthLoginForUser = async ({ userId, providerSlug }) => {
     });
 };
 
-export const exchangeOAuthLoginForUser = async ({ userId, code, state }) => {
+export const exchangeOAuthLoginForUser = async ({ userId, code, state, iss }) => {
     if (!code || !state) {
         throw new Error('oauthcodemissing');
     }
@@ -517,6 +520,9 @@ export const exchangeOAuthLoginForUser = async ({ userId, code, state }) => {
     const callbackUrl = new URL(stateData.redirectUri);
     callbackUrl.searchParams.set('code', code);
     callbackUrl.searchParams.set('state', state);
+    if (iss) {
+        callbackUrl.searchParams.set('iss', iss);
+    }
 
     const tokens = await oidc.authorizationCodeGrant(configuration, callbackUrl, {
         pkceCodeVerifier: stateData.codeVerifier,
diff --git a/frontend/src/views/auth/OAuthCallbackView.vue b/frontend/src/views/auth/OAuthCallbackView.vue
index 80ebe89..cfdf1f4 100644
--- a/frontend/src/views/auth/OAuthCallbackView.vue
+++ b/frontend/src/views/auth/OAuthCallbackView.vue
@@ -24,7 +24,7 @@ export default {
     methods: {
         ...mapActions(['login']),
         async finishLogin() {
-            const { code, state, error, error_description: errorDescription } = this.$route.query;
+            const { code, state, iss, error, error_description: errorDescription } = this.$route.query;
 
             if (error) {
                 this.hasError = true;
@@ -39,7 +39,11 @@ export default {
             }
 
             try {
-                const response = await apiClient.post('/api/auth/oauth/exchange', { code, state });
+                const payload = { code, state };
+                if (iss) {
+                    payload.iss = iss;
+                }
+                const response = await apiClient.post('/api/auth/oauth/exchange', payload);
                 await this.login({ user: response.data, rememberMe: true });
                 await this.$router.replace('/settings/personal');
             } catch (loginError) {
diff --git a/frontend/src/views/auth/OAuthUserCallbackView.vue b/frontend/src/views/auth/OAuthUserCallbackView.vue
index 5873237..b8244e1 100644
--- a/frontend/src/views/auth/OAuthUserCallbackView.vue
+++ b/frontend/src/views/auth/OAuthUserCallbackView.vue
@@ -25,7 +25,7 @@ export default {
     },
     methods: {
         async finishLinking() {
-            const { code, state, error, error_description: errorDescription } = this.$route.query;
+            const { code, state, iss, error, error_description: errorDescription } = this.$route.query;
 
             if (error) {
                 this.hasError = true;
@@ -43,7 +43,11 @@ export default {
 
             try {
                 this.statusText = 'Authentifizierung wird mit deinem Konto verknüpft...';
-                const response = await apiClient.post('/api/auth/oauth/user/exchange', { code, state });
+                const payload = { code, state };
+                if (iss) {
+                    payload.iss = iss;
+                }
+                const response = await apiClient.post('/api/auth/oauth/user/exchange', payload);
                 
                 this.message = 'Erfolgreich verknüpft!';
                 this.statusText = `${response.data.identity.displayName} wurde erfolgreich hinzugefügt. Du kannst diese Seite jetzt schließen oder zur Sicherheitsseite zurückkehren.`;