Is there a way to better my LDAP filter security

Here is what is happening. I'm passing a value into a directorySearcher filter and it works great, but HP Fortify is complaining that the input is from an untrusted source.

It recommended that I validate it with a RegEx expression, but HP fortify is still not liking the input.  Is there a such thing as a parameterized LDAP value that I can pass, like I do with Oracle queries?

Here is the snippet...


string whitelist = "[_a-zA-Z0-9]{1,30}$";
                Regex pattern = new Regex(whitelist);
                  
                        
                        if (pattern.IsMatch(value))
                {
                              var directorySearcher = new DirectorySearcher();
                    directorySearcher.PropertiesToLoad.Add("orclnetdescstring");
                    directorySearcher.SearchRoot = directoryEntry;
                    directorySearcher.SearchScope = SearchScope.Subtree;                    
                    directorySearcher.Filter = "(&(objectclass=orclNetService)(cn=" + value + "))";
                    searchResult = directorySearcher.FindOne();
                }