Keyword query returning results from non shared site also

I am using KeywordQuery (KQ) to get items from SharePoint. My site structure is as follow:

http://server/site1

http://server/site1/siteA

User Bob has access to all the site (Read) while Alice only has access to site1.

As expected, for Bob the KQ returns results from all site, but for Alice it also returns items of SiteA even she doesn't have access to it.

Could you please specify which parameters am I missing while creating the KQ object.

My KQ object has following properties: Querytext, RowLimit and Select Properties.

UPDATE

Client Context that I am passing to KQ

SharePointContextToken contextToken = TokenHelper.ReadAndValidateContextToken(token, request.Url.Authority);
string accessToken = TokenHelper.GetAccessToken(contextToken, targetWeb.Authority).AccessToken;
clientContext = TokenHelper.GetClientContextWithAccessToken(targetWeb.ToString(), accessToken);