CVE-2022-32830 - An Out-of-Bounds Read Vulnerability in ImageIO Leading to Information Disclosure

When processing images on your iPhone, iPad, or Apple TV, you probably don’t think twice about what could go wrong. But in 2022, Apple patched a sneaky security flaw that could let attackers steal personal information just by sending you a crafty image file. That flaw is known as CVE-2022-32830.

In this deep dive, we'll break down what CVE-2022-32830 is, how attackers could have used it, what Apple did to fix it, provide a simplified example, and link to the official sources.

What is CVE-2022-32830?

CVE-2022-32830 is an out-of-bounds read vulnerability in Apple’s ImageIO framework. ImageIO is part of Apple's core system used to process images — like JPG, PNG, GIF, TIFF, and more — that you view or store on your devices.

Technical summary:  
When ImageIO handled specially crafted image files, it could accidentally read memory outside the intended area. This is called an "out-of-bounds read". The data read could contain sensitive information, such as bits of memory containing private messages, tokens, or other confidential user data.

Apple patched this bug in tvOS 15.6, iOS 15.6, and iPadOS 15.6.  
- Apple Security Update (CVE-2022-32830)

Real-World Scenario

Imagine an attacker sends you a perfectly innocent-looking image—perhaps in an email, an app, or a website link. But that image is actually crafted to trigger the vulnerability within ImageIO. Once your device tries to render the picture, the bug is triggered, and the attacker’s code could read memory on your device it’s not supposed to see.

Result: Some of your personal data, that happens to live in memory near where the image is being processed, gets leaked to the attacker.

What Makes Out-of-Bounds Read Dangerous?

Unlike "out-of-bounds write" (which can corrupt memory or run malicious code), an "out-of-bounds read" typically leaks information. Attackers often chain such leaks with other vulnerabilities for more impact.

Imagine the ImageIO parser code worked like this simplified (and unsafe) example in C

// Vulnerable code
void parse_image(uint8_t* image_data, size_t data_len) {
    uint8_t header[16];
    // ...some code...
    memcpy(header, image_data, 32); // Oops! Only 16 bytes in header array
}

This code copies 32 bytes from image_data into a 16-byte buffer header.  
But the array can only hold 16 bytes. The remaining 16 bytes overwrite other memory areas, causing an out-of-bounds write.

Now, for an out-of-bounds read (as in CVE-2022-32830), imagine this instead

// Vulnerable code (out-of-bounds read)
void read_metadata(uint8_t* buffer, size_t buffer_size, int index) {
    if (index < 100) {  // Assumes 100 elements always
        uint8_t value = buffer[index]; // What if buffer_size < 100?
        // ... use value ...
    }
}

If the image file’s metadata says there should be 100 items, but the buffer only has 50, reading beyond 50 accesses memory outside of buffer—an out-of-bounds read.

How Was It Fixed?

The fix involved better "bounds checking"—making sure the code always verifies the requested index or size is within the actual buffer size.

// Patched code
void read_metadata(uint8_t* buffer, size_t buffer_size, int index) {
    if (index < buffer_size) {  // Proper check!
        uint8_t value = buffer[index];
        // ... use value ...
    }
}

Apple’s release notes state:

Proof-of-Concept Exploit Details

A real attacker would need to craft an image file whose metadata points past the end of the actual data. For example, in a hypothetical malformed JPEG:

When ImageIO reads that extra 30 bytes, it exposes random memory data.

Because Apple doesn’t reveal the source code for ImageIO and this issue is patched, there is no public POC for this exact bug. But the attack method would look like this:

1. Attacker creates a malicious image: Image file includes metadata or chunk sizes larger than the actual data.

Victim opens the file: The vulnerable version of ImageIO reads past the buffer boundary.

3. Private data leak: The attacker (or malware) gets back extra bytes—whatever was in memory nearby.

*In practice: details are more complex, involve precise image format structure, and often chained with other bugs.*

How to Stay Safe

- Update Your Software: Make sure your iPhone, iPad, and Apple TV are running iOS/tvOS/iPadOS 15.6 or newer.
- Be Careful with Images: Even after updating, be cautious opening images from untrusted sources (email, web).
- Stay Informed: Read Apple’s Security Updates regularly.

References

- Apple Security Updates - iOS 15.6
- CVE Record for CVE-2022-32830 (NIST)
- ImageIO (Apple Documentation)

Summary

CVE-2022-32830 was a subtle but potentially impactful bug in how your device handled images. By making sure you keep your Apple devices updated, you stay safe from attacks that can steal your data—even with something as simple as a picture.

If you’re a developer: always do bounds checking, and never trust external file formats blindly!


*This article is an exclusive simplification and breakdown. For the latest details on iOS security, always refer to Apple’s Security Updates.*

Timeline

Published on: 02/27/2023 20:15:00 UTC
Last modified on: 03/07/2023 20:38:00 UTC