Description

An out-of-bounds read issue was addressed with improved input validation. This issue is fixed in iOS 27 and iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, watchOS 27. Processing a maliciously crafted font may result in the disclosure of process memory.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-14T21:17:35.297Z",
  "pubdate": "2026-09-14T21:17:35.297Z",
  "executiveSummary": "This vulnerability is an out-of-bounds (OOB) read flaw originating from improper input validation within the system's font processing architecture. The issue affects a wide range of Apple ecosystem platforms, including iOS 27, iPadOS 27, macOS Golden Gate 27, tvOS 27, visionOS 27, and watchOS 27.\nThe vulnerability allows an attacker to bypass standard memory isolation boundaries, potentially leading to the disclosure of sensitive process memory contents. Exploitation requires the attacker to supply a maliciously crafted font file to a targeted application or system process that parses font data. By triggering the OOB read condition, an attacker may extract remnants of process memory, which could include cryptographic keys, credentials, or other sensitive data residing in the address space of the vulnerable component.\nThe risk is significant due to the nature of font processing, which is often deeply integrated into system rendering engines and can be triggered by common user activities such as viewing documents, browsing web content, or rendering system UI elements. The flaw grants an attacker the capability to perform unauthorized information gathering, which often serves as a foundational step for bypassing Address Space Layout Randomization (ASLR) or other memory protection mechanisms in more complex exploitation chains.",
  "technicalDetails": "The vulnerability is rooted in an insufficient input validation mechanism within the font parsing engine utilized across the listed operating systems. When the font parser encounters a maliciously crafted font file—specifically one containing malformed table headers, offset values, or glyph descriptors—it fails to properly bound the memory read operations associated with that font's metadata.\nThe attack flow initiates when an application or system service parses the attacker-controlled font file. The font parser attempts to access internal structures or glyph data by calculating memory offsets based on values embedded in the font file header. Because the parser lacks strict bounds checking, it validates these offsets against an incorrect or overly permissive range. When a specially crafted offset points outside the allocated buffer for the font data, the system performs an OOB read.\nDuring the exploitation sequence, the parser dereferences the calculated memory address and returns data from adjacent memory locations back to the calling process. If the application exposes this returned font information to the attacker—such as through rendering artifacts, error messages, or internal data streams—the attacker can effectively dump the contents of the process memory.\nThe primary impact is the unauthorized disclosure of process memory. In a modern OS environment, this memory often contains heap pointers, stack canaries, or other dynamic data that are crucial for determining the memory layout of the process. By successfully leaking these pointers, an attacker can reliably defeat ASLR, thereby facilitating the development of reliable arbitrary code execution exploits. The vulnerability does not require authentication or elevated privileges to initiate, as the font parsing process typically runs within the context of the user application or the system font server, both of which are exposed to untrusted input from standard file handling or network-based document viewing."
}