CVE-2016-1813

Imagine your device has a sensitive “switch” used for handling graphics-related operations. This flaw lets a specially crafted app either run harmful code at a higher level than it should, or make the device crash. It’s like someone finding a way to pull a lever inside a locked room using a fake key they made.

This matters if you run or manage older Apple devices on iOS, OS X/macOS, tvOS, or watchOS versions prior to the fixed releases listed for this CVE. It’s primarily a concern for devices that can run apps (including apps you might download or receive), since the trigger is a crafted app. There’s no indication in the findings that this is reachable without first running a crafted app, so the realistic risk is tied to app usage on those older OS versions.

This is AMBER because there is a public exploit available, meaning attackers could realistically use it where vulnerable devices still exist. The likelihood is also rising per the available prediction data, even though it’s not confirmed as KEV-listed. If any staff devices are still on pre-fix iOS/macOS/tvOS/watchOS versions, prioritize updates.

Confirm exposure (what to check):

• Identify every Apple device your business uses for work: iPhone/iPad (iOS), Mac (OS X/macOS), Apple TV (tvOS), and Apple Watch (watchOS).
• For each device, record the current OS version.

Compare against fixed versions:

• iOS: fixed in 9.3.2 (apply iOS 9.3.2+)
• macOS (OS X): fixed in 10.11.5 (apply 10.11.5+)
• tvOS: fixed in 9.2.1 (apply tvOS 9.2.1+)
• watchOS: fixed in 2.2.1 (apply watchOS 2.2.1+)

Upgrade path / breaking-change notes:

• Plan upgrades via standard Apple “Software Update” mechanisms for each device class.
• Because the fixed versions are from older releases, some devices may not support moving directly to these versions; in that case, upgrade to the newest supported OS for that hardware as your safest path.

Temporary workaround if you cannot patch immediately:

• Reduce risk by limiting app installs to trusted sources and avoid running unknown or newly created apps on affected devices, since the triggering condition in the findings is a crafted app.

CISA due date:

• Not provided (KEV not listed in CISA KEV per the findings).

What to monitor after updates:

• Verify device OS versions match or exceed the fixed versions.
• Watch for repeated crashes or unusual app behavior only on devices that you could not update promptly.

Severity and type: CVE-2016-1813 is a high-severity issue (as described by the provided context) involving CWE-476 (NULL pointer dereference) that can lead to denial of service, and in some cases arbitrary code execution in a privileged context.

Mechanism / attack vector: The vulnerability is in IOAccelSharedUserClient2::page_off_resource. The findings state it can be triggered via a crafted app, leading to either NULL pointer dereference (crash) or arbitrary code execution.

Exploitation status: A public exploit exists (2 known). KEV is not listed in CISA KEV.

Exploit maturity: Public exploit availability suggests attackers can implement the technique without needing extensive bespoke development.

EPSS: A predicted likelihood value was provided, with a rising trend, but this is not treated as proof of active exploitation; KEV/news would override it if present (not present in findings).