The stable-diffusion.cpp library, used for diffusion model inference, contained a heap buffer overflow in its pickle .ckpt file parser within src/model.cpp. Specifically, the BINUNICODE opcode handler misinterpreted the opcode length field due to sign confusion, leading to a potentially very large length passed to memcpy. This could cause immediate heap corruption when processing a maliciously crafted .ckpt file. The vulnerability is identified as CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The issue was resolved in commit master-584-0a7ae07. No official patch or remediation level is explicitly stated beyond this commit. Users are advised to restrict .ckpt file sources and use safer formats if immediate patching is not feasible.

Successful exploitation of this vulnerability could lead to heap corruption, resulting in potential arbitrary code execution, denial of service, or other impacts affecting confidentiality, integrity, and availability. The CVSS 3.1 score of 7.8 reflects high severity with local attack vector, low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability.

A fix is available in stable-diffusion.cpp at commit master-584-0a7ae07. Users and developers should update to this version to remediate the vulnerability. If immediate updating is not possible, only load .ckpt checkpoint files from trusted sources and prefer safer model formats such as .safetensors to reduce risk.