CVE-2020-3837
Apple Multiple Products Memory Corruption Vulnerability
Description
CVE-2020-3837 is a memory corruption vulnerability affecting multiple Apple products including iOS, iPadOS, macOS, tvOS, and watchOS that could allow a malicious application to execute arbitrary code with kernel privileges. The vulnerability exists in the kernel's memory management subsystem, where improper handling of memory objects enables an attacker to corrupt kernel memory and achieve privilege escalation. CISA has added CVE-2020-3837 to its Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. With an EPSS score of 6.4% (90.9th percentile), this vulnerability shows significantly elevated 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 | < 13.3.1 |
| apple | iphone os | < 13.3.1 |
| apple | mac os x | < 10.15.3 |
| apple | tvos | < 13.3.1 |
| apple | watchos | < 6.1.2 |
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/HT210918(Release Notes, Vendor Advisory)
- https://support.apple.com/HT210919(Release Notes, Vendor Advisory)
- https://support.apple.com/HT210920(Release Notes, Vendor Advisory)
- https://support.apple.com/HT210921(Release Notes, Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3837(US Government Resource)
Weakness Type
CWE-787: Out-of-bounds Write
CVE-2020-3837 involves memory corruption in the Apple kernel that results in out-of-bounds memory writes. The vulnerability allows an attacker to manipulate kernel memory objects in a way that causes writes beyond intended memory boundaries, corrupting adjacent kernel data structures and enabling arbitrary code execution at the highest privilege level.
Learn more: CWE-787 — Out-of-bounds Write
Impact Analysis
CVE-2020-3837 presents a broad threat across the Apple ecosystem, as it affects iOS, iPadOS, macOS, tvOS, and watchOS — encompassing iPhones, iPads, Macs, Apple TVs, and Apple Watches. The kernel-level code execution capability means successful exploitation provides the attacker with complete control over the affected device. A locally installed malicious application is required as the attack vector, but the kernel-level impact is devastating: confidentiality is fully compromised as the attacker can access all data including encrypted content protected by the Secure Enclave; integrity is completely at risk as kernel access allows modification of any system component; and availability can be disrupted through persistent system modifications. The EPSS score of 6.4% (90.9th percentile) confirms high exploitation probability, reflecting the cross-platform impact and the value of Apple kernel exploitation capabilities.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2020-3837 in the wild by adding it to the Known Exploited Vulnerabilities catalog on June 27, 2022, with a remediation deadline of July 18, 2022. With an EPSS score of 6.4% (90.9th percentile), this vulnerability shows significantly elevated exploitation probability compared to most CVEs. The multi-platform nature of the vulnerability, affecting five different Apple operating systems, makes it particularly attractive for threat actors seeking broad Apple device compromise. Kernel memory corruption vulnerabilities in Apple platforms are commonly used in sophisticated exploit chains for surveillance operations against targeted individuals.
Remediation
- Update all affected Apple devices immediately: Install the latest security updates for iOS, iPadOS, macOS, tvOS, and watchOS that contain the fix for CVE-2020-3837. The vulnerability was addressed in updates released in early 2020.
- Enable automatic security updates on all Apple devices: Configure all Apple devices to automatically install security updates to ensure timely patching of kernel-level vulnerabilities.
- Implement application installation restrictions: Use MDM policies or Apple Configurator to restrict the installation of applications from untrusted sources, as exploitation requires a locally installed malicious application.
- Deploy endpoint detection for Apple devices: Implement mobile threat detection solutions that can identify suspicious application behavior and potential kernel exploitation attempts on managed Apple devices.
- Enable Lockdown Mode for high-risk individuals: For users at elevated risk of targeted surveillance attacks, Apple's Lockdown Mode provides additional kernel attack surface reduction.
Technical Details
CVE-2020-3837 is a memory corruption vulnerability in the kernel shared across Apple's operating system platforms — iOS, iPadOS, macOS, tvOS, and watchOS. The vulnerability stems from improper handling of memory objects in the kernel, where incorrect memory management operations allow an attacker-controlled application to corrupt kernel memory structures. The memory corruption can be leveraged to overwrite critical kernel data such as function pointers, object metadata, or process credentials, ultimately enabling the attacker to execute arbitrary code with kernel privileges. The shared kernel codebase across Apple's platforms means a single vulnerability affects devices ranging from iPhones and iPads to Macs and Apple Watches. The local attack vector through a malicious application means the exploit is typically deployed as part of a multi-stage attack chain where initial code execution is obtained through a separate vulnerability or social engineering, and CVE-2020-3837 provides the kernel privilege escalation needed for full device compromise.
Frequently Asked Questions
Is CVE-2020-3837 being actively exploited?
Yes. CISA has confirmed active exploitation of CVE-2020-3837 by adding it to the Known Exploited Vulnerabilities catalog. The EPSS score of 6.4% (90.9th percentile) indicates significantly elevated exploitation probability. Apple device users should ensure all devices are running the latest patched firmware.
What products are affected by CVE-2020-3837?
CVE-2020-3837 affects multiple Apple products including iOS, iPadOS, macOS, tvOS, and watchOS. This means iPhones, iPads, Macs, Apple TVs, and Apple Watches are all potentially vulnerable if running unpatched firmware versions.
How do I fix CVE-2020-3837?
Update all affected Apple devices to the security updates released in early 2020 that address CVE-2020-3837. Enable automatic security updates on all Apple devices. Implement MDM restrictions on application installation.
How severe is CVE-2020-3837?
CVE-2020-3837 is a high-severity kernel memory corruption vulnerability with an EPSS score of 6.4% (90.9th percentile) and confirmed active exploitation. The cross-platform impact across five Apple operating systems and the kernel-level code execution capability make this a critical patching priority for all Apple device environments.
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