ImageMagick has Memory Leak in coders/ashlar.c

Root

Cause

The vulnerability is a memory leak in the WriteASHLARImage function within coders/ashlar.c. When an exception is thrown during the encoding process, the allocated memory for internal structures — specifically an ImageInfo structure — is not properly freed, as the cleanup path fails to release the allocation. This was addressed in commit a253d1b124ebdcc2832daac6f9a35c362635b40e by restructuring the allocation and deallocation of write_info to ensure it is always released [4].

Attack

Surface

The ASHLAR encoder is invoked when ImageMagick processes images in certain formats or through scripting. An attacker would need to supply a crafted image that triggers an exception during encoding, possibly from malformed metadata or over-large dimensions. No authentication is required if the software is used in a service that accepts user-submitted images, such as a web application or batch processing pipeline.

Impact

Repeatedly triggering the leak can exhaust available memory on the target system, leading to a denial of service (DoS) condition. While this does not allow arbitrary code execution, it can disrupt availability for other processes sharing the same memory space.

Mitigation

ImageMagick version 7.1.2-15 contains the fix [1][2]. Users should upgrade to this version or later. Magick.NET version 14.10.3 also includes the corresponding fix as part of a security release [3]. No workarounds other than patching are documented.