Bug 2567538 (CVE-2026-70659)

Summary: CVE-2026-70659 stable-diffusion.cpp: stable-diffusion.cpp: Arbitrary code execution via crafted imatrix file
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerability-draftAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in stable-diffusion.cpp. An attacker can trigger a heap-based buffer overflow by convincing a user to load a specially crafted importance matrix (.imatrix) file. Because the application reuses internal memory buffers without resizing them when encountering duplicate tensor entries, out-of-bounds data is written to the heap. This flaw can lead to arbitrary code execution, memory corruption, or a Denial of Service (DoS) crash.
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Description OSIDB Bzimport 2026-11-05 22:05:47 UTC 
stable-diffusion.cpp is a pure C/C++ library for running diffusion model (Stable Diffusion, Flux, Wan, Qwen Image, Z-Image, and more) inference. From master-742-1a13107 until master-763-4fcc6fe, IMatrixCollector::load_imatrix in src/runtime/imatrix.cpp reuses the values and counts vectors for entries with the same tensor name but resizes them only when they are empty. An untrusted .imatrix file can provide a small nval for the first entry and a larger nval for a second entry with the same name, causing the accumulation loop to write attacker-controlled floating-point and integer values beyond both heap buffers. Loading the file through the --imat-in conversion path can corrupt the heap or crash the process before a model is required. This issue is fixed in master-763-4fcc6fe.