Apple OS image parsing: out-of-bounds write in Apple image processing (CVE-2025-43300) #shorts

Summary

Today on the Cyber Secure Podcast, we cover CVE-2025-43300—a zero-day vulnerability in Apple’s image processing libraries actively exploited in highly sophisticated attacks. Apple has released emergency security updates for iOS, iPadOS and multiple versions of macOS to remediate an out-of-bounds write issue that can lead to memory corruption when handling a malicious image file. If you use Apple devices, this is one vulnerability you’ll want to address immediately.

Product details

This flaw impacts several Apple operating environments: macOS Sonoma prior to 14.7.8, macOS Ventura before 13.7.8, macOS Sequoia below 15.6.1, iOS versions earlier than 18.6.2, iPadOS up to 17.7.10, and iPadOS 18.6.2. Apple issued software updates—Sonoma 14.7.8, Ventura 13.7.8, Sequoia 15.6.1, iOS 18.6.2 and iPadOS 17.7.10/18.6.2—to close this critical gap across desktop and mobile platforms.

Vulnerability type summary

CVE-2025-43300 is a memory corruption vulnerability due to an out-of-bounds write during image file processing. By feeding a specially crafted image to the system, an attacker can overwrite memory regions outside the intended buffer, enabling arbitrary code execution or denial-of-service conditions.

Details of the vulnerability

Apple’s image rendering component lacked proper bounds checking on certain image metadata fields. A malicious image can trigger an out-of-bounds write, corrupting memory and potentially executing attacker-supplied payloads. Apple has confirmed reports of targeted exploits in an “extremely sophisticated attack” against specific individuals, underscoring both the complexity of the exploit and the real-world risk. The vulnerability was assigned CVE-2025-43300 and patched on August 21, 2025.

Conclusion

If you run iOS, iPadOS or macOS, install Apple’s latest security updates without delay to close CVE-2025-43300. Regularly check for firmware updates, avoid opening suspicious images, and maintain a layered defense strategy. Staying current with patches is your first line of defense against zero-day threats and advanced targeted attacks.

Watch the full video on YouTube: CVE-2025-43300

Remediation and exploitation details

This chain involves the following actors

  • Threat Actor: Designs and distributes the malicious image to trigger the vulnerability.
  • Victim User: Receives or previews the crafted image, unknowingly initiating the exploit.

This following systems are involved

  • iOS Image Processing Library (Decodes and renders image files for display on iPhone devices): Handles image parsing, thumbnail generation, and memory management.
  • iPadOS Image Processing Library (Decodes and renders image files for display on iPad devices): Handles image parsing, thumbnail generation, and memory management.
  • macOS Image Processing Library (Decodes and renders image files for display on Mac computers): Handles image parsing, thumbnail generation, and memory management.

Attack entry point

  • Malicious Image File: A specially crafted image containing manipulated header fields and embedded payload designed to overflow internal buffers.

Remediation actions

User or IT Administrator
Install the Apple security updates to patch the out-of-bounds write flaw
iOS 18.6.2, iPadOS 17.7.10 and 18.6.2, macOS Sonoma 14.7.8, Ventura 13.7.8, Sequoia 15.6.1

Exploitation actions

Out-of-bounds write via malformed image header

Threat Actor
Crafts an image with corrupted dimension and metadata fields to exceed the expected buffer size
iOS Image Processing Library
Examples:
  • Set width and height values far larger than the allocated buffer length

Social engineering with automatic thumbnail rendering

Threat Actor
Delivers the malicious image through a messaging app or email, leveraging automatic preview features
iOS Messaging Service
Examples:
  • Embed the image in a text message that loads previews without explicit user action

Background image parsing

Victim User
Receives or previews the message containing the malicious image
iOS Notification and Preview Engine
Examples:
  • Notification banner triggers image decode in memory immediately upon delivery

Buffer overflow leading to adjacent memory corruption

iOS Image Processing Library
Processes the malformed image, performing an unchecked write past the end of a buffer
iOS Kernel Memory Manager
Examples:
  • Overwrite function pointers or metadata structures used by the image decoder

Return oriented programming chain

Threat Actor
Redirects execution flow by overwriting a return address or function pointer
iOS Runtime Environment
Examples:
  • Chain small code snippets already present in memory to achieve arbitrary code execution

Post-exploitation persistence

Threat Actor
Executes arbitrary code to install a persistent backdoor
Compromised Device
Examples:
  • Write a launch agent on disk or modify system configurations to maintain access

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-43300
Description
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in macOS Sonoma 14.7.8, macOS Ventura 13.7.8, iPadOS 17.7.10, macOS Sequoia 15.6.1, iOS 18.6.2 and iPadOS 18.6.2. Processing a malicious image file may result in memory corruption. Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals.
Provider
apple
CWE / problem types
Processing a malicious image file may result in memory corruption. Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals.
Affected Software Versions
Apple:macOS:[{'version': 'unspecified', 'status': 'affected', 'lessThan': '14.7', 'versionType': 'custom'}],Apple:macOS:[{'version': 'unspecified', 'status': 'affected', 'lessThan': '13.7', 'versionType': 'custom'}],Apple:iOS and iPadOS:[{'version': 'unspecified', 'status': 'affected', 'lessThan': '18.6', 'versionType': 'custom'}],Apple:iPadOS:[{'version': 'unspecified', 'status': 'affected', 'lessThan': '17.7', 'versionType': 'custom'}],Apple:macOS:[{'version': 'unspecified', 'status': 'affected', 'lessThan': '15.6', 'versionType': 'custom'}]
Date Published
2025-08-21T00:27:21.442Z
Last Updated
2025-08-22T03:55:38.332Z