CVE-2021-30883
Apple Multiple Products Memory Corruption Vulnerability
Description
CVE-2021-30883 is a memory corruption vulnerability affecting Apple iOS, macOS, watchOS, and tvOS that could allow for arbitrary code execution. The vulnerability exists in the IOMobileFrameBuffer kernel extension, which handles display frame buffer operations. A malicious application can exploit this flaw to execute arbitrary code with kernel privileges, gaining full control over the affected device. Apple confirmed that this vulnerability may have been actively exploited at the time of disclosure. CISA has added CVE-2021-30883 to its KEV catalog, and the EPSS percentile of 68.5% indicates significant exploitation probability.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| apple | ipados | < 14.8.1; >= 15.0, < 15.0.2 |
| apple | iphone os | < 14.8.1; >= 15.0, < 15.0.2 |
| apple | macos | >= 11.0, < 11.6.1; 12.0 |
| apple | tvos | < 15.1 |
| apple | watchos | < 8.1 |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://support.apple.com/en-us/HT212846(Vendor Advisory)
- https://support.apple.com/en-us/HT212868(Vendor Advisory)
- https://support.apple.com/en-us/HT212869(Vendor Advisory)
- https://support.apple.com/en-us/HT212872(Vendor Advisory)
- https://support.apple.com/en-us/HT212874(Vendor Advisory)
- https://support.apple.com/en-us/HT212876(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30883(US Government Resource)
Weakness Type
CWE-787: Out-of-bounds Write
CWE-787 describes a weakness where a product writes data past the end or before the beginning of the intended memory buffer. In CVE-2021-30883, the IOMobileFrameBuffer kernel extension in Apple operating systems contains a memory corruption vulnerability that allows a crafted application to write outside intended memory boundaries, leading to kernel-level code execution.
Learn more: CWE-787 — Out-of-bounds Write
Impact Analysis
CVE-2021-30883 enables kernel-level code execution across multiple Apple platforms, including iOS, macOS, watchOS, and tvOS. The vulnerability requires a local application to trigger, but no user interaction beyond running the malicious application is needed. Successful exploitation grants the attacker kernel privileges, providing complete control over the device, including the ability to bypass all platform security mechanisms, access all user data, install persistent surveillance software, and modify system behavior. The broad platform coverage means that iPhones, iPads, Macs, Apple Watches, and Apple TVs are all potentially affected. The EPSS percentile of 68.5% reflects significant exploitation probability, and Apple acknowledged potential active exploitation when releasing the patch. CISA has confirmed active exploitation and added CVE-2021-30883 to the KEV catalog.
Exploit Maturity
Apple acknowledged that CVE-2021-30883 may have been actively exploited when the patch was released in October 2021. CISA has confirmed active exploitation and added it to the Known Exploited Vulnerabilities catalog with a remediation deadline of June 13, 2022. The EPSS percentile of 68.5% indicates significant exploitation probability. The vulnerability in IOMobileFrameBuffer is part of a class of kernel extension flaws that have been repeatedly targeted by both jailbreak developers and commercial spyware vendors. Proof-of-concept analysis and exploitation details became available after the patch release, with security researchers demonstrating the kernel memory corruption mechanism. The vulnerability's presence across iOS, macOS, watchOS, and tvOS creates a wide attack surface for sophisticated threat actors.
Remediation
- Update all Apple devices to the latest software versions that address CVE-2021-30883: iOS 15.0.2 or later, macOS Monterey 12.0.1 or later, watchOS 8.1 or later, and tvOS 15.1 or later. Apply updates per vendor instructions as required by CISA's KEV catalog.
- Enable automatic updates on all Apple devices to ensure timely deployment of security patches for kernel vulnerabilities.
- Restrict application installation to trusted sources (App Store) and avoid sideloading applications from unknown sources.
- Deploy mobile device management (MDM) solutions in enterprise environments to enforce update compliance and monitor for jailbreak or kernel exploitation indicators.
- For high-risk environments, consider enabling Apple's Lockdown Mode (available in newer iOS/macOS versions) to reduce the kernel attack surface by disabling certain features and system extensions.
Technical Details
CVE-2021-30883 is a memory corruption vulnerability in the IOMobileFrameBuffer kernel extension, which manages display frame buffer operations across Apple's operating systems. The vulnerability is classified under CWE-787 (Out-of-bounds Write), where the kernel extension fails to properly validate input parameters during frame buffer operations, allowing a malicious application to write data beyond the intended memory buffer boundaries. This out-of-bounds write can corrupt adjacent kernel memory structures, which an attacker can manipulate to redirect execution flow and achieve arbitrary kernel code execution. The attack requires local code execution (a malicious application) but no additional user interaction. Since IOMobileFrameBuffer runs as a kernel extension with full kernel privileges, successful exploitation immediately grants the attacker the highest privilege level on the system. The vulnerability affects iOS, macOS, watchOS, and tvOS because the IOMobileFrameBuffer component is shared across Apple's operating system family.
Frequently Asked Questions
Is CVE-2021-30883 being actively exploited?
Apple acknowledged that CVE-2021-30883 may have been actively exploited when the patch was released. CISA has confirmed active exploitation and added it to the KEV catalog. The EPSS percentile of 68.5% indicates significant exploitation probability.
What products are affected by CVE-2021-30883?
CVE-2021-30883 affects multiple Apple platforms: iOS (before 15.0.2), macOS (before Monterey 12.0.1), watchOS (before 8.1), and tvOS (before 15.1). This means iPhones, iPads, Macs, Apple Watches, and Apple TVs are all potentially affected.
How do I fix CVE-2021-30883?
Update all Apple devices to iOS 15.0.2+, macOS Monterey 12.0.1+, watchOS 8.1+, or tvOS 15.1+ respectively. Enable automatic updates for ongoing protection. See the Remediation section for additional security measures.
How severe is CVE-2021-30883?
CVE-2021-30883 is a kernel memory corruption vulnerability with an EPSS percentile of 68.5%. It enables arbitrary code execution with kernel privileges through a malicious application, providing complete device control. The broad impact across iOS, macOS, watchOS, and tvOS, combined with confirmed active exploitation, makes it a significant threat to the entire Apple ecosystem.
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