Maintaining accurate platform version data despite frozen User-Agent versions.
If you have noticed that devices running iOS 26 suddenly appear as iOS 18 in your analytics, you are not alone.
In recent updates Apple has started freezing the OS version information contained in the User-Agent string as part of its privacy measures to reduce device fingerprinting.
This change means the version information provided by browsers on iOS and iPadOS is no longer reliable.
To ensure accuracy in the data we return, we have introduced a new property called IsPlatformVersionFrozen.
What IsPlatformVersionFrozen does
The IsPlatformVersionFrozen property indicates whether the platform vendor, such as Apple, is providing a frozen or incorrect platform version in the User-Agent evidence.
When the value is True, 51Degrees detects that the version in the User-Agent is not genuine and instead returns the most likely real platform version.
When the value is False, the version reported by the User-Agent can be trusted.
View the full property description in the Property Dictionary.
The background: Apple freezes platform versions
Starting with iOS 26, Apple changed the information that Safari and all WebKit-based browsers send in their User-Agent strings.
Our Data Team tested real devices and identified examples where the User-Agent reports iPhone OS 18, even though the actual iOS version is 26.
Apple has decoupled the platform version from the real OS version to make the User-Agent more consistent and less revealing.
As a result, any solution that relies only on User-Agent data would incorrectly identify these devices as iOS 18.
How 51Degrees corrected the version data
51Degrees Device Detection has been updated to identify and correct these frozen versions.
When a browser reports an outdated or frozen platform version, the system determines the most likely true version using additional evidence supplied with the request, such as the browser name and browser version. This approach is reliable because our Data Team has validated how User-Agent strings and related evidence appear across different browsers and apps on each platform version.
At the same time, the new IsPlatformVersionFrozen property is set to True to provide visibility that this correction has been applied.
This update is now live across all 51Degrees services.
This change applies to all iOS and iPadOS browsers affected by Apple’s update, not only Safari. For example, Opera GX on iOS 26.0.1 presents a similar User-Agent and is now correctly identified.
Why this matters
Accurate platform version data supports a wide range of use cases including analytics, troubleshooting, and feature targeting.
Without this correction, OS version reports would show misleading results and could affect business or development decisions.
The IsPlatformVersionFrozen property helps by:
- Providing accurate OS version information even when the User-Agent is frozen
- Offering transparency so developers know when an inferred value has been used
- Bot patterns
- Preparing for future browser changes that may also freeze or obscure version data
Are you ready to try 51Degrees?
The introduction of IsPlatformVersionFrozen is just one of many innovations 51Degrees makes every year.
If you want the only ISO-accredited provider of all-in-one Device Detection and IP Intelligence services, look no further.
Contact us to see how 51Degrees can help your business make better data-driven decisions.