CVE-2026-59956 OpenImageIO: Heap-buffer-overread in IffInput::readimg() when ZBUFFER flag is set
A heap-buffer-overread in OpenImageIO allows attackers to disclose adjacent heap memory or cause a crash via crafted IFF images.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-59956?
CVE-2026-59956 is a medium-severity memory corruption vulnerability in Openimageio Openimageio, published on 18 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
OpenImageIO is a toolset for reading, writing, and manipulating image files of any image file format relevant to VFX / animation. Prior to 3.0.20.0, 3.1.15.0, and 3.2.0.3-beta1, An uncompressed 16-bit iff image with a z-buffer makes iffinput::readimg() allocate a temporary scanline from m_header.rgba_count but copy from it using m_header.pixel_bytes(), whose stride also includes z-buffer bytes. the oversized memcpy reads beyond the temporary heap buffer and copies adjacent memory into the output image, resulting in a crash or disclosure of adjacent heap data. The affected implementation is identified by src/iff.imageio/iffinput.cpp, IffInput::readimg(), m_header.rgba_count, and m_header.pixel_bytes(), which define the relevant source path, functions, state, and trigger. This issue is fixed in versions 3.0.20.0, 3.1.15.0, and 3.2.0.3-beta1.
Weakness: CWE-125
Which versions are affected by CVE-2026-59956?
It affects 1 product.
Products include Openimageio Openimageio.
How do I fix CVE-2026-59956?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-59956 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59956 exists.
Other vulnerabilities in Openimageio Openimageio
Sources
Also known as DEBIAN-CVE-2026-59956, GHSA-hjfv-gvxc-qgvh, UBUNTU-CVE-2026-59956.