The stable-diffusion.cpp library, used for diffusion model inference, contained a heap buffer overflow in its pickle .ckpt parser within src/model.cpp. The vulnerability arises from sign confusion on the opcode length field in the BINUNICODE handler, which can cause memcpy to use an excessively large length derived from a negative signed value. This leads to immediate heap corruption when processing a maliciously crafted .ckpt file. The issue is resolved in version master-584-0a7ae07. No official remediation level or patch link is provided, but updating to this version addresses the vulnerability. Alternative mitigation includes restricting .ckpt file sources to trusted origins and using safer formats such as .safetensors.

Successful exploitation allows an attacker to cause heap corruption via a crafted .ckpt file, potentially leading to arbitrary code execution, denial of service, or other high-impact outcomes. The CVSS 3.1 score is 7.8 (High), reflecting local attack vector with low complexity, no privileges required, user interaction needed, and high confidentiality, integrity, and availability impacts.

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