Threat Intelligence Database

A heap buffer overflow vulnerability exists in the pickle .ckpt parser of stable-diffusion.cpp prior to version master-584-0a7ae07. The issue arises from missing validation when parsing newline-delimited fields, allowing a crafted .ckpt file without expected newlines to cause heap corruption. Exploitation requires loading a malicious .ckpt file from an untrusted source. The vulnerability has been fixed in version master-584-0a7ae07. Until updated, users should avoid loading .ckpt files from untrusted sources and prefer safer formats like .safetensors.

A heap-based buffer overflow vulnerability exists in the pickle .ckpt parser of stable-diffusion.cpp prior to version master-584-0a7ae07. The flaw is due to sign confusion in the BINUNICODE opcode length field, allowing a crafted .ckpt file to trigger a large memcpy operation causing heap corruption. This vulnerability has been fixed in version master-584-0a7ae07. Until updating, users should only load .ckpt files from trusted sources and prefer safer formats like .safetensors.

stable-diffusion.cpp is a pure C/C++ library for running diffusion model (Stable Diffusion, Flux, Wan, Qwen Image, Z-Image, and more) inference. Versions prior to master-584-0a7ae07 are vulnerable to heap buffer overflow in SHORT_BINUNICODE parsing for PyTorch checkpoint files. The pickle .ckpt parser in src/model.cpp contained a heap buffer overflow vulnerability in the SHORT_BINUNICODE opcode handler. The issue was caused by sign confusion on the opcode length field. A crafted .ckpt file could trigger memcpy with a very large length derived from a negative signed value, causing immediate heap corruption. Any application using affected stable-diffusion.cpp releases to load untrusted .ckpt model files could be vulnerable. A malicious checkpoint file could cause heap corruption through memcpy with an attacker-controlled length. This may lead to process crash and could potentially be leveraged for code execution depending on heap layout. The attack requires the victim or application to load a .ckpt file from an untrusted source, such as a downloaded model from a model sharing site. The issue has been resolved in version master-584-0a7ae07. If developers are unable to immediately update their applications they can work around this issue by not loading .ckpt checkpoint files from untrusted sources, and referring to trusted model sources and safer formats such as .safetensors where possible.

stable-diffusion.cpp is a pure C/C++ library for running diffusion model (Stable Diffusion, Flux, Wan, Qwen Image, Z-Image, and more) inference. Versions prior to master-584-0a7ae07 are vulnerable to an out-of-bounds reads error through PyTorch checkpoint pickle opcode parsing. The pickle .ckpt parser in src/model.cpp did not consistently check that enough input remained before reading opcode arguments or advancing the parser buffer with a crafted or truncated .ckpt file. Throughout the pickle parser, opcode handlers advanced the parser position with expressions such as buffer += N without first checking that buffer + N <= buffer_end. A truncated file could therefore cause reads past the end of the metadata buffer. LibFuzzer found crashes in under one second using malformed checkpoint inputs. Any application using affected stable-diffusion.cpp releases to load untrusted .ckpt model files could be vulnerable. The attack requires the victim or application to load a .ckpt file from an untrusted source, such as a downloaded model from a model sharing site. This issue has been fixed in version master-584-0a7ae07. If developers are unable to immediately update their applications, they can work around this issue by ensuring they do not load .ckpt checkpoint files from untrusted sources. They should prefer trusted model sources and safer formats such as .safetensors where possible.