Is this update vulnerable to CVE-2023-23529: an anonymous researcher

You device is vulnerable only if you have/had Jailbroken your device.

I have been updating my devices ever since I bought my first device in 2009. iPhone 3Gs, 4S, 5, 6, SE (1st Gen), 7, 8 and iPhone 12 Pro, iPad Pro, Macbook Air 2019.

I never had any issues with any iOS, iPadOS, or macOS till date.

I would personally recommend everyone to update their devices instead of listening to rumours from people who may not have kept their devices free from any spurious softwares.

iOS / iPadOS devices cannot be hacked or infected with Virus / Malware / Spyware if it is updated to the latest iOS/iPadOS unless you have intentionally downloaded spurious software or unauthorized apps directly from the internet and installed them on your device or/and have Jailbroken.