CVE-2021-30807
Apple Multiple Products Memory Corruption Vulnerability
Description
CVE-2021-30807 is a high-severity memory corruption vulnerability in Apple IOMobileFrameBuffer that allows an application to execute arbitrary code with kernel privileges. The vulnerability affects Apple iOS, iPadOS, macOS, and watchOS and was addressed with improved memory handling. Apple has acknowledged that this issue may have been actively exploited. CISA has added this vulnerability to its Known Exploited Vulnerabilities catalog. With an EPSS score of 17.40% (95.0th percentile), CVE-2021-30807 has a high 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 | < 14.7.1 |
| apple | iphone os | < 14.7.1 |
| apple | macos | < 11.5.1 |
| apple | watchos | < 7.6.1 |
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/HT212622(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT212623(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT212713(Release Notes, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30807(Third Party Advisory, US Government Resource)
Weakness Type
CWE-787: Out-of-bounds Write
Out-of-bounds Write occurs when software writes data beyond the intended boundaries of a buffer. In CVE-2021-30807, the IOMobileFrameBuffer kernel extension in Apple operating systems contains a memory corruption vulnerability that allows a malicious application to write beyond allocated memory boundaries, corrupting kernel data structures and enabling privilege escalation to kernel-level code execution.
Learn more: CWE-787 — Out-of-bounds Write
Impact Analysis
CVE-2021-30807 carries a CVSS 3.1 score of 7.8 (HIGH), reflecting a significant privilege escalation threat. The attack vector is local, requiring a malicious application to be installed on the device, with low attack complexity and no privileges beyond a normal app, though user interaction is needed to install the app. Confidentiality (High): kernel-level access exposes all data on the device, including encrypted credentials, keychain entries, and data from other applications. Integrity (High): kernel code execution allows modification of any system component, installation of persistent rootkits, and tampering with security mechanisms. Availability (High): kernel-level exploitation can crash or destabilize the entire device. The EPSS score of 17.40% (95.0th percentile) indicates high exploitation probability, and Apple's acknowledgment of active exploitation emphasizes the criticality of patching.
Exploit Maturity
CVE-2021-30807 is confirmed as actively exploited, with Apple stating awareness of reports that this issue may have been actively exploited. CISA has included this vulnerability in the Known Exploited Vulnerabilities catalog, with federal agencies required to remediate by 2021-11-17. The EPSS score of 17.40% (95.0th percentile) indicates high exploitation probability. While specific public exploit code is not widely documented in the references, the vulnerability's nature as a kernel privilege escalation primitive makes it highly valuable for exploit chains, as it can be combined with an initial code execution vulnerability to achieve full device compromise.
Remediation
- Apply vendor patches immediately as mandated by CISA KEV: Apply updates per vendor instructions. Update Apple iOS and iPadOS to version 14.7.1 or later, macOS Big Sur to 11.5.1 or later, and watchOS to 7.6.1 or later.
- Verify that all Apple devices across the organization have been updated to the patched versions. Implement MDM policies that enforce minimum OS version requirements.
- As an interim mitigation, restrict app installations to only trusted sources (App Store) and implement application whitelisting where possible to prevent malicious applications from being installed.
- Monitor devices for indicators of kernel-level compromise, including unexpected reboots, unusual process activity with elevated privileges, and signs of jailbreaking or root access attempts.
- Implement defense-in-depth strategies including endpoint detection and response (EDR) solutions for Apple devices, network monitoring for suspicious traffic patterns, and regular security assessments of the device fleet.
Technical Details
CVE-2021-30807 is a memory corruption vulnerability in IOMobileFrameBuffer, an Apple kernel extension responsible for managing the device display's frame buffer. The vulnerability was addressed with improved memory handling in the patched versions. The flaw allows a malicious application running in userspace to trigger a memory corruption condition in the kernel through crafted IOMobileFrameBuffer requests, ultimately achieving arbitrary code execution with kernel privileges. This type of vulnerability is particularly dangerous as it bypasses all application sandboxing and security boundaries. The CVSS vector (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) indicates a local attack requiring user interaction (installing a malicious app), but with low complexity once the app is running.
Frequently Asked Questions
Is CVE-2021-30807 being actively exploited?
Yes. Apple has acknowledged active exploitation of CVE-2021-30807, and CISA has listed it in the Known Exploited Vulnerabilities catalog with a remediation deadline of 2021-11-17.
What products are affected by CVE-2021-30807?
CVE-2021-30807 affects Apple iOS and iPadOS (< 14.7.1), macOS Big Sur (< 11.5.1), and watchOS (< 7.6.1). All Apple devices running these operating systems are potentially vulnerable.
How do I fix CVE-2021-30807?
Update Apple iOS and iPadOS to version 14.7.1 or later, macOS Big Sur to 11.5.1 or later, and watchOS to 7.6.1 or later. Implement MDM policies to enforce timely updates across all managed devices.
How severe is CVE-2021-30807?
CVE-2021-30807 has a CVSS 3.1 score of 7.8 (HIGH). It enables kernel-level code execution from a malicious application, effectively granting complete control over the device. The EPSS score of 17.40% indicates high exploitation probability.
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