CVE-2017-17783

Vulnerability

A buffer over-read vulnerability exists in GraphicsMagick's ReadPALMImage function in coders/palm.c (line 1024). The issue occurs when QuantumDepth is 8, leading to a read beyond the allocated buffer. This affects GraphicsMagick version 1.3.27a and possibly earlier versions. The bug was reported in SourceForge bug #529 [2].

Exploitation

An attacker can exploit this vulnerability by providing a specially crafted PALM image file. No authentication or special privileges are required; the attack can be performed by convincing a user to process the malicious image with GraphicsMagick (e.g., via mogrify command). The AddressSanitizer output from the report confirms a global-buffer-overflow read of size 1 [2].

Impact

Successful exploitation leads to a denial of service (application crash) due to the buffer over-read. There is no evidence of arbitrary code execution; the impact is limited to availability compromise.

Mitigation

The vulnerability is fixed in GraphicsMagick version 1.3.23-1ubuntu0.5 for Ubuntu 16.04 LTS [1]. Users should upgrade to this or a later version. For other distributions, consult the respective package maintainers. No workaround is available aside from avoiding untrusted PALM images until patching.