Description

A memory corruption vulnerability was addressed with improved locking. This issue is fixed in iOS 18.7.10 and iPadOS 18.7.10, iOS 26.6.1 and iPadOS 26.6.1, macOS Tahoe 26.6.2. Processing maliciously crafted web content may lead to an unexpected Safari crash.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "3.1",
  "pubDate": "2026-08-17T22:17:22.873Z",
  "pubdate": "2026-08-17T22:17:22.873Z",
  "executiveSummary": "This advisory details a memory corruption vulnerability residing within multiple Apple operating systems, specifically affecting iOS, iPadOS, and macOS environments. The flaw manifests during the processing of maliciously crafted web content, potentially triggered within the context of the Safari browser engine or associated web processing components.\nThe primary security impact resulting from successful exploitation of this defect is an unexpected application crash, manifesting as a denial of service condition for the affected browser process. However, memory corruption vulnerabilities traditionally carry severe risk implications regarding arbitrary code execution if memory manipulation primitives can be leveraged reliably by an adversary.\nAffected systems encompass iOS 18.7.10, iPadOS 18.7.10, iOS 26.6.1, iPadOS 26.6.1, and macOS Tahoe 26.6.2. Attacker capabilities rely on the ability to deliver maliciously crafted web content to a targeted user, typically requiring user interaction such as navigating to a hostile webpage or rendering hostile advertising assets.\nOrganizations and end-users face moderate operational risks due to potential service disruption. The integration of improved locking mechanisms indicates that synchronization issues, such as race conditions or concurrent memory access flaws, were identified as the root vector, necessitating immediate software updates to ensure system integrity and stability.",
  "technicalDetails": "The vulnerability stems from a memory corruption flaw resulting from inadequate synchronization and concurrency control within the affected web content processing pipelines. The root cause has been addressed by the vendor through the implementation of improved locking mechanisms, pointing directly to a concurrency defect, such as a race condition, time-of-check to time-of-use (TOCTOU) error, or thread-unsafe resource management during parallel execution paths.\nThe vulnerable component handles the parsing and rendering of web content within Safari. When processing maliciously crafted web content designed to trigger race conditions or improper memory access patterns, concurrent threads or asynchronous execution routines attempt to read, write, or deallocate shared memory regions without adequate mutual exclusion guarantees. This leads to anomalous memory states, such as use-after-free, double-free, or heap corruption conditions.\nThe attack flow proceeds as follows: First, an attacker hosts maliciously crafted web content on an accessible remote server or injects it via a compromised ad network. Second, the victim utilizes Safari to navigate to the hostile URL or load a webpage containing the malicious payload. Third, the rendering engine processes the structured data, triggering concurrent operations on shared memory objects. Due to insufficient locking mechanisms, a race condition occurs, resulting in corrupted pointers or invalid memory dereferences.\nPrivilege and authentication requirements are minimal from the perspective of the attacker; no prior authentication is required, and execution occurs within the standard sandbox constraints associated with web content processes. Network exposure is broad, as the attack vector requires only the capability to deliver arbitrary web traffic over standard network protocols to the client browser. The immediate payload behavior observed is an unhandled exception or memory fault leading to an unexpected Safari crash. Advanced adversaries might attempt to pivot from the primitive memory corruption state to achieve arbitrary code execution, bypassing platform mitigations depending on the exact nature of the corrupted heap metadata."
}