CVE-2020-9991 Denial of service in iCloud for Windows

What is CVE-2020-9991?

CVE-2020-9991 is a high-severity denial of service vulnerability in Apple Icloud, published on 8 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

This issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, iOS 14.0 and iPadOS 14.0, iCloud for Windows 7.21, tvOS 14.0. A remote attacker may be able to cause a denial of service.

Which versions are affected by CVE-2020-9991?

It affects 6 products.

Products include Apple Icloud, Apple Ipados, Apple Iphone Os, Apple Mac Os X, Apple Tvos, Apple Watchos.

How do I fix CVE-2020-9991?

No fix has been published for CVE-2020-9991 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-9991 being exploited?

There is no known exploitation of CVE-2020-9991 in the wild and no public exploit code.

Other vulnerabilities in Apple Icloud

• CVE-2019-8506 Apple Multiple Products Type Confusion Exploited High 8.8
• CVE-2020-27932 Apple Multiple Products Type Confusion Exploited High 7.8
• CVE-2019-8746 Memory corruption in iOS Critical 9.8
• CVE-2019-8749 Memory corruption in iOS Critical 9.8
• CVE-2019-8756 Memory corruption in iOS Critical 9.8

All Apple Icloud vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-5pgw-jw9q-8cfq, UBUNTU-CVE-2020-9991.