What is the _cs_mk_aa cookie?
Ensures Adobe dimensions and eVars are set only once every 30 minutes. Stores the value of the csMatchingKey which is a random number plus timestamp in milliseconds.
Our October 2026 scan found it on 3 sites (0% of the 2,450 we scanned), set before any consent.
- Purpose
- Analytics
- Belongs to
- ContentSquare
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- Under a day (vendor says: 30 minutes)
Sites that set _cs_mk_aa before consent
The highest-ranked 3 of 3 sites.
- ford.com17 tracking companies
- poste.it1 tracking company
- toyota.com19 tracking companies
Related cookies
Other cookies from ContentSquare.
How to stop it
Declining non-essential cookies in a site's consent banner should stop _cs_mk_aa being set on later visits. Blocking third-party cookies in your browser settings stops the third-party kind everywhere, and clearing cookies for a site removes any it already set.
Description from the Open Cookie Database (Apache 2.0).
Understanding this page
- How cookie lifetimes work, and why a 13-month _ga matters
What a cookie's "expires" field actually controls, why Google Analytics ships a 2-year default that many sites cut down to 13 months, and how Safari's 7-day cap on script-set cookies changes the picture.
- First-party vs third-party cookies (and why "first-party" still tracks you)
What the distinction actually means technically, why browsers only block one of the two, and how CNAME cloaking, server-side tagging and cookies like _ga let sites keep tracking under their own domain.
- How to block or limit trackers
Browser privacy settings, content blockers, Global Privacy Control and clearing cookies compared honestly — what each one actually stops, what it doesn't, and what it costs you in return.