Apple iOS and iPadOS Kernel Out-of-Bounds Write Vulnerability (CVE-2021-30900) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTApple iOS and iPadOS devices running versions prior to 14.8.1 or 15.1
A malicious local application can exploit this vulnerability to execute arbitrary code with kernel privileges, leading to complete device compromise
Immediately update affected devices to iOS/iPadOS 14.8.1, 15.1, or later versions
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to upgrade the operating system to iOS/iPadOS 14.8.1 or 15.1 and above. For enterprise environments, administrators should push the update command via MDM.
<!-- MDM OS Update Command Payload Example -->
<dict>
<key>RequestType</key>
<string>ScheduleOSUpdate</string>
<key>Updates</key>
<array>
<dict>
<key>ProductKey</key>
<string>iOS15.1Patch</string>
<key>InstallAction</key>
<string>Default</string>
</dict>
</array>
</dict>2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict profile installations and sideloading of applications using MDM policies.
# Restrict configuration profiles and sideloading via MDM policy commands
security-policy-tool --set-restriction --allowUIConfigurationProfileInstallation false
security-policy-tool --set-restriction --allowAppInstallation true --requireAppStore false3. Log Audit & IoC Verification Commands
Use the following script to audit connected iOS devices and verify if they are running a vulnerable OS version.
# Bash script utilizing libimobiledevice to check connected iOS device version
#!/bin/bash
echo '[*] Checking connected iOS device version...'
if ! command -v ideviceinfo &> /dev/null; then
echo '[!] libimobiledevice is not installed. Please install it to run this audit.'
exit 1
fi
PRODUCT_VERSION=$(ideviceinfo -k ProductVersion)
echo "[+] Detected iOS/iPadOS Version: $PRODUCT_VERSION"
if [[ '$PRODUCT_VERSION' < '14.8.1' ]] || [[ '$PRODUCT_VERSION' == '15.0'* ]]; then
echo '[WARNING] Device is VULNERABLE to CVE-2021-30900. Update immediately!'
else
echo '[OK] Device is patched or running a secure version.'
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-30900) is an out-of-bounds write issue (CWE-787) residing within the memory management subsystem of the Apple iOS and iPadOS kernel. The root cause is insufficient bounds checking when handling input parameters or index offsets during memory write operations. This allows an attacker to overwrite adjacent memory structures outside the allocated buffer boundaries.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by executing a specially crafted malicious application on the target device. By invoking specific system calls with malformed arguments, the application triggers the out-of-bounds write condition within the kernel space. This memory corruption can be leveraged to overwrite critical kernel data structures, such as process credentials, allowing the attacker to bypass the application sandbox and escalate privileges to the kernel level.
3. Infrastructure & Business Impact
As this vulnerability is listed in the CISA KEV catalog, it has been actively exploited in the wild. In an enterprise environment, compromised mobile devices pose a severe threat to corporate data security. Attackers can leverage kernel-level access to exfiltrate sensitive corporate communications, access credentials, and use the compromised device as a pivot point to target internal corporate networks.
Official Vendor Advisories & References
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 14.8.1 and iPadOS 14.8.1, iOS 15.1 and iPadOS 15.1. A malicious application may be able to execute arbitrary code with kernel privileges.
Frequently Asked SecOps Questions (CVE-2021-30900)
FAQQ1. How critical is CVE-2021-30900 and is it actively exploited in the wild?
CVE-2021-30900 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 5.2%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-30900?
Primary impacted vendors include apple across ios, ipados. Scope summary: All Apple devices running iOS/iPadOS versions prior to 14.8.1, or iOS/iPadOS 15.0 and 15.0.1
Q3. What temporary mitigations or workarounds exist for CVE-2021-30900 before patching?
[Mitigation] Immediately update affected devices to iOS/iPadOS 14.8.1, 15.1, or later versions Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-30900
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