Casio pauses parts of its Watches app over PHP flaw

If your Casio smartwatch app has been acting up this week, there's a reason. Casio has temporarily suspended some functions and services of its Casio Watches smartphone app as a precaution against the critical security flaws in PHP, the web programming language behind a large share of the world's websites, Notebookcheck reports, citing an official notice from the company.

What Casio says

According to the notice, dated 22 October, the suspension started on 21 October 2026 (Japan time). Casio says parts of the Casio Watches service run on PHP, so it took the affected functions offline to protect customer information. Two points matter most for owners:

• Casio says it has not confirmed any unauthorised access to the service and no leak of customer information.
• It stresses that the problem lies in technology used by web services worldwide and is not specific to Casio.

The company apologised and said it is working to restore the services as quickly as possible, but it has not given a date.

What it means for your watch

The Casio Watches app connects Bluetooth models such as many G-Shock, Edifice and Pro Trek watches to a phone, where it can sync the time and change supported settings; what's available depends on the model. Casio's notice doesn't list which functions are switched off, so it's unclear how much each model is affected. The watches themselves keep working as watches; features that depend on Casio's online service are the ones at risk.

Why PHP

The timing lines up with PHP2Shell, the pair of critical PHP flaws disclosed this month, which security firms say are now being exploited. We covered the PHP patches and what site owners should do when they shipped. Casio's decision to pull services offline before confirming any intrusion is a cautious but sensible move.

Until Casio publishes a restoration date, there's little owners need to do: keep the app updated, and be wary of unexpected emails or messages claiming to be from Casio asking you to log in. If you're weighing up a connected watch, our comparison of a fitness tracker vs a smartwatch explains which features depend on a phone app and which don't.