CVE-2026-70659
stable-diffusion.cpp: Heap out-of-bounds write in the imatrix loader (`load_imatrix`) via a duplicate tensor name
What happened?
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.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| stable-diffusion.cppleejet | affected: < master-763-4fcc6fe | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-70659
- https://github.com/leejet/stable-diffusion.cpp/security/advisories/GHSA-6q7q-2v9c-x8m7
- https://github.com/leejet/stable-diffusion.cpp/pull/1750
- https://github.com/leejet/stable-diffusion.cpp/commit/4fcc6fef10c6f686801c6e257b22cd6a3deb906b
- https://github.com/leejet/stable-diffusion.cpp/releases/tag/master-763-4fcc6fe