CVE-2023-32439
Apple Multiple Products WebKit Type Confusion Vulnerability
Description
CVE-2023-32439 is a type confusion vulnerability in Apple's WebKit engine that affects Safari, iOS, iPadOS, macOS Ventura, and WebKitGTK+. The flaw allows an attacker to achieve arbitrary code execution by tricking a victim into processing maliciously crafted web content. Apple has acknowledged that CVE-2023-32439 may have been actively exploited in the wild, classifying it as a zero-day vulnerability at the time of disclosure. CISA has added this vulnerability to the Known Exploited Vulnerabilities catalog, and the EPSS score of 0.99% (76th percentile) reflects a moderate probability of exploitation across the broader threat landscape.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| apple | safari | < 16.5.1 |
| apple | ipados | < 15.7.7; >= 16.0, < 16.5.1 |
| apple | iphone os | < 15.7.7; >= 16.0, < 16.5.1 |
| apple | macos | >= 13.0, < 13.4.1 |
| webkitgtk | webkitgtk\+ | < 2.42.3 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://security.gentoo.org/glsa/202401-04(Third Party Advisory)
- https://support.apple.com/en-us/HT213811(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT213813(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT213814(Release Notes, Vendor Advisory)
- https://support.apple.com/en-us/HT213816(Release Notes, Vendor Advisory)
- https://support.apple.com/kb/HT213814(Vendor Advisory)
- https://support.apple.com/kb/HT213816(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-32439(US Government Resource)
Weakness Type
CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')
CWE-843 occurs when a program accesses a resource using a type that is incompatible with the actual type of that resource, leading to undefined behavior. In CVE-2023-32439, WebKit's JavaScript engine mishandles type information during web content processing, allowing an attacker to supply crafted content that triggers a type confusion condition, ultimately leading to memory corruption and arbitrary code execution.
Learn more: CWE-843 — Access of Resource Using Incompatible Type
Impact Analysis
CVE-2023-32439 is rated High severity with a CVSS score of 8.8 under CVSS v3.1, indicating significant risk to affected systems. The vulnerability is remotely exploitable over the network without requiring any authentication or special privileges from the attacker. User interaction is required, as the victim must navigate to or otherwise process the attacker's malicious web content, but the attack complexity is low, meaning the exploit works reliably without special conditions. Successful exploitation delivers high impact to confidentiality, integrity, and availability: Confidentiality (High) allows the attacker to read sensitive data from the compromised device, Integrity (High) enables modification of system data and files, and Availability (High) means the device or application can be crashed. The combination of network-based exploitation, no privilege requirements, and confirmed active exploitation makes this vulnerability a serious threat to any organization with unpatched Apple devices or systems running affected WebKitGTK+ versions.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2023-32439 by including it in the Known Exploited Vulnerabilities catalog with a remediation deadline of July 14, 2023. Apple's security advisory explicitly states that the company is aware of reports that this issue may have been actively exploited, confirming its use as a zero-day weapon. While no dedicated public proof-of-concept exploit code is referenced in the available advisories, the confirmed active exploitation demonstrates that threat actors possess working exploits. The EPSS score of 0.99% places CVE-2023-32439 in the 76th percentile, indicating a moderate to elevated probability of exploitation activity compared to the overall vulnerability population.
Remediation
- Apply Apple's security updates immediately: upgrade to iOS 16.5.1 / iPadOS 16.5.1, iOS 15.7.7 / iPadOS 15.7.7, macOS Ventura 13.4.1, or Safari 16.5.1 as documented in Apple's advisories (HT213811, HT213813, HT213814, HT213816).
- Update WebKitGTK+ on Linux systems: for systems running WebKitGTK+, apply the patches referenced in the Gentoo security advisory (GLSA 202401-04) or the corresponding distribution-specific update. Debian and Fedora users should check their package managers for the latest webkitgtk+ updates.
- Deploy web content filtering as an interim mitigation to reduce exposure to malicious web content. Configure enterprise proxies or secure web gateways to block access to known malicious domains and to inspect JavaScript-heavy content for anomalous behavior.
- Monitor endpoint detection systems for signs of WebKit exploitation, including unexpected process crashes in Safari or WebKit-based applications, abnormal memory access patterns, and any post-exploitation indicators such as unusual outbound network connections or privilege escalation attempts.
- Enable Lockdown Mode on iOS for high-value targets or users in elevated-risk environments to reduce the attack surface of WebKit and other system components against sophisticated exploits.
Technical Details
CVE-2023-32439 is a type confusion vulnerability (CWE-843) in Apple's WebKit rendering engine. Type confusion occurs when a program allocates or initializes a resource as one type but subsequently accesses it as an incompatible type, leading to out-of-bounds memory access or corruption. In this case, the WebKit JavaScript engine improperly handles type checks during the processing of web content, allowing a crafted payload to cause the engine to misinterpret object types in memory. Attack Vector (Network) confirms the vulnerability is exploitable remotely through a malicious webpage, while Attack Complexity (Low) indicates the exploit does not depend on race conditions or specialized system configurations. Privileges Required (None) means the attacker needs no prior access, and User Interaction (Required) limits exploitation to scenarios where the victim visits a compromised or attacker-controlled website. The resulting memory corruption from the type confusion enables arbitrary code execution within the WebKit process, with Scope (Unchanged) confining the initial impact to the WebKit sandbox, though further exploitation chains could extend the attacker's reach.
Frequently Asked Questions
Is CVE-2023-32439 being actively exploited?
Yes, CVE-2023-32439 has been confirmed as actively exploited. CISA added it to the Known Exploited Vulnerabilities catalog with a remediation deadline of July 14, 2023, and Apple has acknowledged reports of active exploitation in its security advisories.
What products are affected by CVE-2023-32439?
CVE-2023-32439 affects Apple Safari (versions before 16.5.1), iOS and iPadOS (versions before 16.5.1 and 15.7.7), macOS Ventura (versions before 13.4.1), and WebKitGTK+ on Linux platforms. Any application that embeds WebKit for rendering web content may also be vulnerable.
How do I fix CVE-2023-32439?
Update affected Apple products to iOS 16.5.1, iPadOS 16.5.1, macOS Ventura 13.4.1, or Safari 16.5.1. For Linux systems running WebKitGTK+, apply the latest security patches from your distribution's package repository. Refer to Apple's HT213811, HT213813, HT213814, and HT213816 advisories for details.
How severe is CVE-2023-32439?
CVE-2023-32439 is rated High severity with a CVSS score of 8.8 out of 10. The vulnerability enables remote arbitrary code execution through crafted web content, and confirmed active exploitation in the wild significantly elevates the practical risk for organizations with unpatched devices.
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