CVE-2024-27834: Apple Safari Privilege Escalation Flaw

CVE-2024-27834 Overview

CVE-2024-27834 is a security vulnerability affecting multiple Apple products and WebKit-based browsers that allows an attacker with arbitrary read and write capability to bypass Pointer Authentication (PAC). Pointer Authentication is a hardware security feature on ARM-based Apple devices designed to protect against memory corruption exploits by cryptographically signing pointers. This vulnerability undermines a critical security boundary that protects against code execution attacks.

Critical Impact

An attacker who has already achieved arbitrary read/write access can leverage this vulnerability to bypass Pointer Authentication, potentially enabling further exploitation such as code execution or privilege escalation on Apple devices.

Affected Products

• Apple Safari (versions prior to 17.5)
• Apple iOS and iPadOS (versions prior to 17.5)
• Apple macOS Sonoma (versions prior to 14.5)
• Apple tvOS (versions prior to 17.5)
• Apple watchOS (versions prior to 10.5)
• WebKitGTK
• WPE WebKit
• Fedora 39 and 40

Discovery Timeline

• May 14, 2024 - CVE-2024-27834 published to NVD
• November 4, 2025 - Last updated in NVD database

Technical Details for CVE-2024-27834

Vulnerability Analysis

This vulnerability represents a weakness in the implementation of Pointer Authentication Code (PAC) checks within the WebKit engine used by Safari and other Apple products. PAC is a security feature introduced in ARM64e architecture that adds cryptographic signatures to pointers, making it significantly harder for attackers to exploit memory corruption vulnerabilities by tampering with function pointers or return addresses.

The flaw allows an attacker who has already achieved arbitrary read and write capabilities to craft inputs or manipulate memory in ways that bypass the PAC verification process. This effectively neutralizes a key exploit mitigation, making it easier to chain with other vulnerabilities for more severe attacks such as arbitrary code execution.

The vulnerability requires local access and existing memory manipulation capabilities, which typically means it would be used as part of a multi-stage attack chain rather than as a standalone exploit.

Root Cause

The root cause stems from insufficient validation checks in the PAC implementation. Apple addressed the issue with improved checks, indicating that certain code paths did not properly validate the integrity of authenticated pointers before use. This oversight allowed attackers to forge or manipulate pointers in ways that should have been detected and blocked by the PAC mechanism.

Attack Vector

The attack requires local access to the target system and assumes the attacker has already achieved arbitrary read and write memory capabilities, typically through a separate vulnerability. With these prerequisites in place, the attacker can manipulate memory structures in a way that circumvents PAC validation, enabling subsequent exploitation steps such as:

• Redirecting control flow to attacker-controlled code
• Bypassing Return-Oriented Programming (ROP) mitigations
• Escalating privileges through JIT compilation attacks in WebKit

The vulnerability is exploited locally and does not require user interaction once the attacker has the necessary memory access primitives. The primary impact is on system integrity, as bypassing PAC undermines a fundamental security control.

Detection Methods for CVE-2024-27834

Indicators of Compromise

• Unusual memory access patterns in WebKit or Safari processes indicating memory corruption attempts
• Crash logs showing PAC-related failures or unexpected pointer verification errors
• Evidence of exploit chains targeting WebKit vulnerabilities followed by PAC bypass attempts
• Anomalous JavaScript execution patterns that may indicate JIT spraying or heap manipulation

Detection Strategies

• Monitor for unusual WebKit process behavior including unexpected memory allocation patterns
• Implement behavioral analysis to detect multi-stage exploit chains targeting browser engines
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts
• Review system crash reports for PAC verification failures that may indicate exploitation attempts

Monitoring Recommendations

• Enable comprehensive logging for Safari and WebKit-based applications
• Monitor for known exploit chain patterns that combine memory corruption with PAC bypass techniques
• Implement network monitoring to detect potential delivery mechanisms for exploit code
• Utilize SentinelOne's behavioral AI to detect exploitation attempts in real-time

How to Mitigate CVE-2024-27834

Immediate Actions Required

• Update all affected Apple devices to the latest available versions immediately
• Upgrade Safari to version 17.5 or later
• Update iOS and iPadOS to version 17.5 or later
• Update macOS Sonoma to version 14.5 or later
• Update tvOS to version 17.5 and watchOS to version 10.5 or later
• For Linux systems using WebKitGTK or WPE WebKit, apply the latest security updates from your distribution

Patch Information

Apple has released security patches addressing this vulnerability across all affected platforms. The patches include improved validation checks for Pointer Authentication. Detailed information is available in the following security advisories:

• Apple Security Update HT214101 - tvOS 17.5
• Apple Security Update HT214102 - iOS 17.5 and iPadOS 17.5
• Apple Security Update HT214103 - Safari 17.5
• Apple Security Update HT214104 - watchOS 10.5
• Apple Security Update HT214106 - macOS Sonoma 14.5

Fedora users should apply updates via the Fedora Package Announcement.

Workarounds

• Limit use of WebKit-based browsers on unpatched systems until updates can be applied
• Restrict access to untrusted web content on vulnerable devices
• Implement network-level filtering to block known malicious content targeting WebKit vulnerabilities
• Consider using alternative browsers that do not rely on WebKit on affected platforms where possible
• Deploy endpoint protection solutions to detect and block exploitation attempts