🔐 fix: Stop Deriving the Exchange Origin from the Referer on SSO Callbacks

src/server/auth.oauth.test.ts

@@ -243,6 +243,57 @@ describe('oauthExchangeFn', () => {
     );
   });
 
+  it('derives the exchange Origin from the serving host when the callback carries the IdP referer', async () => {
+    sessionState.data = { codeVerifier: 'verifier-123' };
+    requestHeaders.set('referer', 'https://login.microsoftonline.com/');
+    requestHeaders.set('host', 'example.com');
+    requestHeaders.set('x-forwarded-proto', 'https');
+    fetchMock.mockResolvedValueOnce(
+      jsonResponse(200, {
+        token: 'jwt-token',
+        user: { id: 'user-1', role: 'ADMIN', email: 'admin@example.com' },
+      }),
+    );
+
+    const result = await oauthExchangeFn({ data: { code: 'c'.repeat(64) } });
+
+    expect(result).toEqual({
+      error: false,
+      user: { id: 'user-1', role: 'ADMIN', email: 'admin@example.com' },
+    });
+    expect(fetchMock).toHaveBeenCalledWith('http://librechat.test/api/admin/oauth/exchange', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        Origin: 'https://example.com',
+      },
+      body: JSON.stringify({ code: 'c'.repeat(64), code_verifier: 'verifier-123' }),
+    });
+  });
+
+  it('uses the first x-forwarded-proto value when the proxy chain appends multiple', async () => {
+    sessionState.data = { codeVerifier: 'verifier-123' };
+    requestHeaders.set('host', 'example.com');
+    requestHeaders.set('x-forwarded-proto', 'https, http');
+    fetchMock.mockResolvedValueOnce(
+      jsonResponse(200, {
+        token: 'jwt-token',
+        user: { id: 'user-1', role: 'ADMIN', email: 'admin@example.com' },
+      }),
+    );
+
+    await oauthExchangeFn({ data: { code: 'd'.repeat(64) } });
+
+    expect(fetchMock).toHaveBeenCalledWith('http://librechat.test/api/admin/oauth/exchange', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        Origin: 'https://example.com',
+      },
+      body: JSON.stringify({ code: 'd'.repeat(64), code_verifier: 'verifier-123' }),
+    });
+  });
+
   it('does not consume the one-time LibreChat exchange code when the PKCE verifier was lost', async () => {
     sessionState.data = {};
 

src/server/auth.ts

@@ -21,23 +21,25 @@ function extractCookieValue(response: Response, name: string): string | undefine
   return undefined;
 }
 
+/**
+ * Resolves the admin panel's own origin for LibreChat's exchange-code origin binding.
+ *
+ * Never derived from the `referer` header: when a proxy or client drops the `Origin`
+ * header, the referer identifies whatever page or IdP initiated the request (e.g.
+ * Azure EntraID's login.microsoftonline.com on an IdP-initiated callback), not the
+ * panel itself. Forwarding a foreign origin makes LibreChat reject the exchange code
+ * as expired even though authentication succeeded. The panel's own serving origin is
+ * always derivable from `host` plus the first `x-forwarded-proto` value.
+ */
 function getRequestOrigin(): string | undefined {
   const origin = getRequestHeader('origin');
   if (origin) return origin;
 
-  const referer = getRequestHeader('referer');
-  if (referer) {
-    try {
-      return new URL(referer).origin;
-    } catch {
-      return undefined;
-    }
-  }
-
   const host = getRequestHeader('host');
   if (!host) return undefined;
 
-  const proto = getRequestHeader('x-forwarded-proto') ?? 'http';
+  const forwardedProto = getRequestHeader('x-forwarded-proto');
+  const proto = forwardedProto?.split(',')[0]?.trim() || 'http';
   return `${proto}://${host}`;
 }