CVE-2024-40815 Overview
CVE-2024-40815 is a race condition vulnerability affecting multiple Apple operating systems. The flaw allows an attacker with arbitrary read and write capability to bypass Pointer Authentication (PAC), an exploit-mitigation feature that cryptographically signs pointers to prevent tampering. Apple addressed the issue with additional validation across iOS, iPadOS, macOS, tvOS, and watchOS. The vulnerability is tracked under [CWE-362] (Concurrent Execution using Shared Resource with Improper Synchronization) and [CWE-352]. Apple published fixes on July 29, 2024.
Critical Impact
An attacker with existing arbitrary read/write primitives can defeat Pointer Authentication, enabling reliable code-reuse attacks and elevating memory corruption bugs into full exploitation chains.
Affected Products
- Apple iOS and iPadOS versions prior to 17.6
- Apple macOS Sonoma prior to 14.6 and macOS Ventura prior to 13.6.8
- Apple tvOS prior to 17.6 and watchOS prior to 10.6
Discovery Timeline
- 2024-07-29 - CVE-2024-40815 published to the National Vulnerability Database (NVD)
- 2024-07-29 - Apple released security updates in iOS 17.6, iPadOS 17.6, macOS Sonoma 14.6, macOS Ventura 13.6.8, tvOS 17.6, and watchOS 10.6
- 2026-06-17 - Last updated in the NVD database
Technical Details for CVE-2024-40815
Vulnerability Analysis
Pointer Authentication (PAC) is a hardware-assisted mitigation on Apple Silicon and ARMv8.3-A devices. PAC embeds a cryptographic Message Authentication Code (MAC) in unused pointer bits to detect tampering before dereference. Attackers who obtain arbitrary read and write primitives typically cannot forge valid signed pointers, which forces them to reuse existing signed pointers. This flaw weakens that guarantee.
The vulnerability stems from a race condition in the code paths that produce or consume signed pointers. Concurrent access to shared state allows an attacker to observe or manipulate a pointer between the signing and validation steps. Apple's advisory states the fix adds additional validation to eliminate the window.
Root Cause
The root cause is improper synchronization ([CWE-362]) around Pointer Authentication operations. Two threads or execution contexts can access shared pointer state without adequate locking, creating a Time-of-Check to Time-of-Use (TOCTOU) window. During that window, an attacker with an existing memory corruption primitive can substitute or duplicate a validly signed pointer into an unrelated context, bypassing PAC's integrity guarantee.
Attack Vector
Exploitation requires an attacker to already possess arbitrary read and write capability, typically obtained through a separate memory corruption vulnerability. The attacker then races the PAC validation logic to substitute a target pointer with an attacker-controlled but legitimately signed value. Once PAC is bypassed, the attacker can pivot to arbitrary code execution using return-oriented programming (ROP) or jump-oriented programming (JOP) despite the mitigation being present. The Common Vulnerability Scoring System (CVSS) vector reflects high attack complexity because the race window is narrow and the prerequisite primitives are non-trivial.
No public proof-of-concept code is available, and technical specifics beyond Apple's advisories have not been published. Refer to the Apple Support Document HT214117 for platform-specific details.
Detection Methods for CVE-2024-40815
Indicators of Compromise
- Apple devices running iOS, iPadOS, macOS, tvOS, or watchOS builds prior to the July 29, 2024 security updates
- Unexpected kernel panics or process crashes referencing PAC failures in system logs (/var/log/DiagnosticReports/)
- Presence of unsigned or previously unseen binaries executing with elevated entitlements
Detection Strategies
- Enroll managed Apple devices in a Mobile Device Management (MDM) platform and enforce minimum OS build reporting to identify unpatched endpoints.
- Ingest macOS Unified Log entries and EndpointSecurity events into a Security Information and Event Management (SIEM) system to flag anomalous exception traces referencing ptrauth or EXC_BAD_ACCESS with PAC codes.
- Correlate crash reports across the fleet to surface repeated Pointer Authentication failures that may indicate active exploitation attempts.
Monitoring Recommendations
- Monitor process execution telemetry on macOS for unexpected child processes launched by privileged system daemons.
- Track OS version distribution and alert on devices that remain below iOS 17.6, iPadOS 17.6, macOS Sonoma 14.6, or macOS Ventura 13.6.8.
- Review authentication and configuration-change events on managed devices for signs of post-exploitation persistence.
How to Mitigate CVE-2024-40815
Immediate Actions Required
- Update all Apple devices to iOS 17.6, iPadOS 17.6, macOS Sonoma 14.6, macOS Ventura 13.6.8, tvOS 17.6, or watchOS 10.6 or later.
- Inventory endpoints via MDM and prioritize patch deployment for devices handling sensitive data or exposed to untrusted content.
- Restrict installation of unsigned or side-loaded applications that could deliver the arbitrary read/write primitive required for exploitation.
Patch Information
Apple released coordinated updates on July 29, 2024. Consult the vendor advisories: Apple Support Document HT214117, HT214119, HT214120, HT214122, and HT214124. The fix introduces additional validation to close the race window in the affected code path.
Workarounds
- No vendor-supplied workaround exists; patching is the only supported remediation.
- Reduce attack surface by disabling or restricting exposure to untrusted network content and third-party applications until updates are applied.
- Enable Lockdown Mode on iOS and macOS for high-risk users to reduce the availability of attack surface used to gain the prerequisite memory primitives.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
