Safari 27 is reported to block known ad-platform trackers at the IP-address level, cutting the connection to those servers before any measurement data leaves the browser. According to PPC Land, the protection targets destination IP ranges tied to platforms such as Bing's UET endpoint and LinkedIn's ad trackers, which means the request never completes rather than being stripped after the fact.
The practical consequence for advertisers is direct. Many teams responded to earlier Safari restrictions by routing tracker calls through their own domains, using first-party subdomains or server-side proxies so the request looked like it belonged to the site rather than a third-party ad platform. Because Safari 27 keys the block to the destination IP address, PPC Land reports that those first-party proxy and subdomain workarounds do not evade it. The browser resolves where the connection is actually going and stops it regardless of the domain on the front.
How the IP-level block reportedly works
The earlier generation of tracking protection largely operated on domains and cookies. A tracker hosted on a recognisable third-party domain could be flagged, and its storage could be capped or cleared. Advertisers adapted by moving the endpoint onto infrastructure they controlled, which broke the domain-matching logic that the protections relied on.
Per PPC Land's account, Safari 27 changes the layer at which the decision happens. Instead of asking which domain a request claims to come from, it looks at the IP range the connection is heading toward. If that range belongs to a known ad-platform server, the connection is refused. A first-party CNAME or a proxy subdomain still resolves to the same destination infrastructure, so re-labelling the front door does not change the address behind it.
The report also notes a delivery detail worth understanding. Apple is said to ship these rules in a separately updated system library rather than inside the browser binary itself. That separation means the block list can be revised without waiting for a full browser release, so the set of targeted IP ranges can move faster than Safari's own version cycle.
Which trackers are named
The specific endpoints called out in the reporting are Bing's UET (Universal Event Tracking) endpoint and LinkedIn's ad trackers. Both are common on B2B and lead-generation sites, where marketers rely on them to measure clicks and conversions from those platforms. When the connection is blocked at the IP layer on Apple devices, the events those tags would have recorded simply never arrive.
Why this matters for measurement
The change adds to a longer pattern of erosion in click and conversion measurement on Apple devices. Every prior workaround assumed the block operated on something the advertiser could relabel, such as a domain or a cookie. An IP-level block removes that assumption, because the advertiser does not control the destination address of the ad platform's own servers.
The effect is uneven rather than total. It applies to Safari, and therefore weighs most on traffic from iPhones, iPads, and Macs where Safari is the default browser. Segments with heavy Apple-device usage will see a larger gap between real activity and recorded activity than segments dominated by other browsers. Reported conversions from campaigns that lean on Bing UET or LinkedIn tracking may understate what actually happened, and the size of the gap depends on how much of the audience is on Apple hardware.
| Layer | Older Safari protection | Safari 27 (reported) |
|---|---|---|
| What is matched | Domains and cookies | Destination IP ranges |
| First-party proxy workaround | Often evaded the block | Does not evade the block |
| Where rules ship | With the browser | Separately updated system library |
What this means for Thai marketers
Thailand has a large iOS user base, so any measurement change that concentrates on Safari and Apple devices is likely to touch a meaningful slice of local traffic. The reporting does not make any Thailand-specific claim, and none should be assumed. The reasonable read is that campaigns measured through Bing UET or LinkedIn tags may show a widening gap between platform-reported conversions and what other data sources record, in proportion to how many users are on Apple devices.
The sensible response is to reduce reliance on any single client-side tag as the source of truth. A durable measurement setup leans on server-side collection and modelled conversions rather than one browser tag firing on the client. If your conversion data flows through a well-structured analytics foundation, a block on one platform's client-side tracker is easier to detect and reason about. Teams reviewing how their conversions are captured can start with a GA4 measurement setup that is not tied to a single vendor's pixel, and align that with how spend is tracked across paid search campaigns so reported numbers can be sanity-checked against independent signals.
FAQ
Does a first-party subdomain still hide the tracker?
According to PPC Land, no. Safari 27 blocks based on the destination IP range, so a first-party subdomain or proxy that still points at the ad platform's servers is caught anyway.
Does this affect all browsers?
The reporting concerns Safari 27. Traffic on other browsers is not described as subject to these specific rules, so the impact is weighted toward Apple devices where Safari is the default.
Can Apple update the block list quickly?
The rules are said to ship in a separately updated system library rather than the browser binary, which lets the targeted IP ranges change without a full browser release.
Measurement on Apple devices keeps getting harder for advertisers who depend on client-side tags. If you want a conversion setup that does not fall over when one platform's tracker is blocked, our team can review how your analytics and campaign tracking fit together and where the blind spots are.
