CVE-2023-32434
Apple Multiple Products Integer Overflow Vulnerability
Description
CVE-2023-32434 is an integer overflow vulnerability in Apple's kernel that affects iOS, iPadOS, macOS, and watchOS. The flaw, caused by insufficient input validation, allows a malicious application to execute arbitrary code with kernel privileges, granting an attacker full control over the affected device. Apple has acknowledged that CVE-2023-32434 may have been actively exploited against versions of iOS released before iOS 15.7, and CISA has added it to the Known Exploited Vulnerabilities catalog. With an EPSS score of 68.28% (99th percentile), this vulnerability represents one of the most likely-to-be-exploited Apple kernel flaws, making immediate patching across all Apple devices critical.
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 | < 15.7.7; >= 16.0, < 16.5.1 |
| apple | iphone os | < 15.7.7; >= 16.0, < 16.5.1 |
| apple | macos | >= 11.0, < 11.7.8; >= 12.0.0, < 12.6.7; >= 13.0, < 13.4.1 |
| apple | watchos | < 8.8.1; >= 9.0, < 9.5.2 |
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
- http://seclists.org/fulldisclosure/2023/Oct/20(Mailing List, Third Party Advisory)
- https://support.apple.com/en-us/HT213808(Vendor Advisory)
- https://support.apple.com/en-us/HT213809(Vendor Advisory)
- https://support.apple.com/en-us/HT213810(Vendor Advisory)
- https://support.apple.com/en-us/HT213811(Vendor Advisory)
- https://support.apple.com/en-us/HT213812(Vendor Advisory)
- https://support.apple.com/en-us/HT213813(Vendor Advisory)
- https://support.apple.com/en-us/HT213814(Vendor Advisory)
- https://support.apple.com/kb/HT213990(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-32434(US Government Resource)
Weakness Type
CWE-190: Integer Overflow or Wraparound
In CVE-2023-32434, an integer overflow occurs in the Apple kernel when processing certain input values without adequate validation. When arithmetic operations produce a result that exceeds the maximum value the integer type can hold, the value wraps around to a small or negative number. In this case, the overflow leads to incorrect memory allocation sizes or buffer calculations, which an attacker can exploit to write beyond allocated memory boundaries and ultimately execute arbitrary code with kernel privileges.
Learn more: CWE-190 — Integer Overflow or Wraparound
Impact Analysis
CVE-2023-32434 carries a CVSS v3.1 score of 7.8 (High severity), reflecting the serious nature of this kernel-level vulnerability across Apple's product ecosystem. The vulnerability is exploitable locally (Attack Vector: Local), typically through a malicious application installed on the device. Low attack complexity means the vulnerability is straightforward to exploit with no special conditions required. No authentication or privileges are needed by the attacker, though user interaction is required — the victim must install or run a malicious application. The impact upon exploitation is devastating: Confidentiality (High) exposes all data on the device including credentials, messages, and encryption keys. Integrity (High) enables the attacker to modify system files, install persistent backdoors, or tamper with any data on the device. Availability (High) means the device can be rendered inoperable or used as a platform for further attacks. The EPSS score of 68.28% (99th percentile) indicates an extremely high probability of active exploitation, placing CVE-2023-32434 among the most exploited Apple vulnerabilities. Apple itself confirmed awareness of active exploitation against pre-iOS 15.7 devices, and the broad range of affected products — spanning iPhones, iPads, Macs, and Apple Watches — amplifies the organizational risk.
Exploit Maturity
CVE-2023-32434 has been actively exploited in the wild, as confirmed by both Apple and CISA, which added it to the Known Exploited Vulnerabilities catalog with a remediation deadline of July 14, 2023. Apple explicitly stated in its advisory that this issue may have been actively exploited against versions of iOS released before iOS 15.7, indicating targeted attacks were observed prior to the patch release. A public disclosure is available via Seclists Full Disclosure, providing additional technical details about the vulnerability. The EPSS score of 68.28% (99th percentile) indicates near-certain exploitation activity, making this one of the most actively targeted Apple kernel vulnerabilities. The ransomware association is classified as unknown, but the kernel-level access achieved through exploitation makes it suitable for a wide range of attack objectives including surveillance, data theft, and persistent device compromise.
Remediation
- Update all Apple devices immediately to the patched versions as specified by Apple: iOS 16.5.1 / iPadOS 16.5.1, iOS 15.7.7 / iPadOS 15.7.7, macOS Ventura 13.4.1, macOS Monterey 12.6.7, macOS Big Sur 11.7.8, watchOS 9.5.2, or watchOS 8.8.1. Per CISA's KEV directive: apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Prioritize devices running older iOS versions (prior to iOS 15.7), as Apple confirmed active exploitation specifically targeting these versions. Verify patch status across your entire Apple device fleet using MDM enrollment data.
- Restrict application installation on managed devices to trusted sources only. Configure MDM policies to prevent sideloading and restrict App Store downloads to vetted applications, reducing the risk of users installing malicious apps that could trigger the integer overflow.
- Monitor for indicators of compromise by reviewing device logs for unusual kernel-level activity, unexpected process privilege escalations, or signs of spyware. Deploy endpoint detection and response (EDR) solutions compatible with Apple devices to detect exploitation attempts.
- Implement defense-in-depth by enabling Lockdown Mode on high-risk devices (available in iOS 16+), enforcing automatic updates through MDM, and segmenting Apple devices from critical infrastructure to limit the blast radius of potential compromise.
Technical Details
CVE-2023-32434 is an integer overflow vulnerability (CWE-190) in the Apple kernel that affects the core operating system across iOS, iPadOS, macOS, and watchOS. The vulnerability occurs when the kernel processes input values that cause an arithmetic operation to exceed the maximum value representable by the integer data type, resulting in a wraparound to a small or negative number. This incorrect value is then used in subsequent memory operations — such as buffer allocation or bounds checking — leading to undersized allocations that can be overflowed by attacker-controlled data. The CVSS vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) indicates that exploitation occurs locally through a malicious application, requires no special privileges, but does need the user to run the malicious app. The low attack complexity reflects that the integer overflow can be triggered reliably without race conditions or other timing-sensitive requirements. Apple addressed the vulnerability with improved input validation, adding proper bounds checking to prevent the integer overflow condition from occurring. The fact that this vulnerability provides kernel-level code execution makes it exceptionally valuable for sophisticated attack campaigns, as kernel access bypasses all application-level sandboxing and security controls on Apple devices.
Frequently Asked Questions
Is CVE-2023-32434 being actively exploited?
Yes, CVE-2023-32434 has been actively exploited in the wild. Apple confirmed awareness of exploitation against iOS versions prior to 15.7, and CISA added it to the Known Exploited Vulnerabilities catalog with a remediation deadline of July 14, 2023. The EPSS score of 68.28% places it in the 99th percentile for exploitation probability.
What products are affected by CVE-2023-32434?
CVE-2023-32434 affects a wide range of Apple products: iOS and iPadOS (versions prior to 16.5.1 and 15.7.7), macOS Ventura (prior to 13.4.1), macOS Monterey (prior to 12.6.7), macOS Big Sur (prior to 11.7.8), watchOS (prior to 9.5.2 and 8.8.1). All Apple devices running these operating systems are vulnerable.
How do I fix CVE-2023-32434?
Update all Apple devices to the latest patched versions: iOS/iPadOS 16.5.1 or 15.7.7, macOS Ventura 13.4.1, macOS Monterey 12.6.7, macOS Big Sur 11.7.8, or watchOS 9.5.2/8.8.1. Prioritize devices running iOS versions older than 15.7, as these were specifically targeted by attackers.
How severe is CVE-2023-32434?
CVE-2023-32434 is rated High severity with a CVSS v3.1 score of 7.8. The vulnerability enables arbitrary code execution with kernel privileges, effectively granting complete device control. With an EPSS score in the 99th percentile and confirmed active exploitation by Apple and CISA, this is among the most critical Apple vulnerabilities requiring immediate remediation.
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