Why did Yahoo text me a verification code?
We'll send a verification code via text message when you create a Yahoo account or make security changes to an existing account. You'll need to enter the verification code when prompted to confirm your account or changes.
If you received a verification code via text but didn't create an account or make security changes, then someone else mistyped their number and accidentally used yours. Don't worry, they won't be able to move forward with your mobile number because they don't have possession of your phone to get the verification code.