There have been multiple reports of malware (specifically from cmi.netseer.com) to Google's Ad Exchange team. Google notified us this morning that they are looking into it and recommended we block this advertiser in our Ad Exchange account. We've done this and are waiting for an update on the fix.
We received an update from Google regarding the malware attack. The advertiser's corporate website, which shares the same domain name as their ad serving infrastructure (but not the same code base) was hacked and infected with malware. The issue has been resolved as of 9:30am PDT.