Apple has released security updates to address two vulnerabilities, said the agency.
It advised users to patch the following products to the latest versions immediately:
iPhone 8 and later iPad Pro (all models) iPad Air 3rd generation and later iPad 5th generation and later iPad mini 5th generation and later macOS VenturaUsers are also encouraged to enable automatic software updates under the settings function in their devices.
Successful exploitation of the vulnerabilities could "allow an attacker to perform arbitrary code execution on affected products", said SingCERT.
The agency issued a similarly worded warning last month, when it also urged Apple users to update their devices to the latest versions immediately, to fix a "zero-day vulnerability" affecting most iPhones and iPads.
Information security and technology news publication Bleeping Computer said an exploitation of the flaw could lead to data corruption, application crashes and memory corruption.