ImageMagick is vulnerable to an integer Overflow in TIM decoder leading to out of bounds read (32-bit only)

Summary

The TIM (PSX TIM) image parser in ImageMagick contains a critical integer overflow vulnerability in the ReadTIMImage function (coders/tim.c). The code reads width and height (16-bit values) from the file header and calculates image_size = 2 * width * height without checking for overflow. On 32-bit systems (or where size_t is 32-bit), this calculation can overflow if width and height are large (e.g., 65535), wrapping around to a small value. This results in a small heap allocation via AcquireQuantumMemory and later operations relying on the dimensions can trigger an out of bounds read.

Vulnerable Code

File: coders/tim.c

width=ReadBlobLSBShort(image);
height=ReadBlobLSBShort(image);
image_size=2*width*height;       // Line 234 - NO OVERFLOW CHECK!

Impact

This vulnerability can lead to Arbitrary Memory Disclosure due to an out of bounds read on 32-bit systems.