diff --git a/api/strategies/samlStrategy.js b/api/strategies/samlStrategy.js
index cab43044b9..ced6c26148 100644
--- a/api/strategies/samlStrategy.js
+++ b/api/strategies/samlStrategy.js
@@ -216,6 +216,15 @@ function createSamlCallback(existingUsersOnly = false) {
         });
       }
 
+      if (user?.samlId && user.samlId !== profile.nameID) {
+        logger.warn(
+          `[samlStrategy] Refused SAML login with a different NameID for user: ${user.email}`,
+        );
+        return done(null, false, {
+          message: ErrorTypes.AUTH_FAILED,
+        });
+      }
+
       const appConfig = user?.tenantId
         ? await resolveAppConfigForUser(getAppConfig, user)
         : baseConfig;
diff --git a/api/strategies/samlStrategy.spec.js b/api/strategies/samlStrategy.spec.js
index 301fee3a87..353ab1df7a 100644
--- a/api/strategies/samlStrategy.spec.js
+++ b/api/strategies/samlStrategy.spec.js
@@ -7,6 +7,7 @@ jest.mock('@librechat/data-schemas', () => ({
   logger: {
     info: jest.fn(),
     debug: jest.fn(),
+    warn: jest.fn(),
     error: jest.fn(),
   },
   hashToken: jest.fn().mockResolvedValue('hashed-token'),
@@ -426,6 +427,23 @@ u7wlOSk+oFzDIO/UILIA
     expect(user.email).toBe(baseProfile.email);
   });
 
+  it('should reject an email match bound to a different NameID', async () => {
+    const { findUser, updateUser } = require('~/models');
+    const existingUser = {
+      _id: 'existing-user-id',
+      provider: 'saml',
+      email: baseProfile.email,
+      samlId: 'original-name-id',
+    };
+    findUser.mockResolvedValueOnce(null).mockResolvedValueOnce(existingUser);
+
+    const result = await validate(baseProfile);
+
+    expect(result.user).toBe(false);
+    expect(result.details.message).toBe(require('librechat-data-provider').ErrorTypes.AUTH_FAILED);
+    expect(updateUser).not.toHaveBeenCalled();
+  });
+
   it('should block login when email exists with different provider', async () => {
     // Set up findUser to return a user with different provider
     const { findUser } = require('~/models');