# CVE-2026-63638: OpenImageIO heap overflow in cineon image parsing

Source: https://junglewise.ai/threats/cve-2026-63638-openimageio-is-a-toolset-for-reading-writing-and-manipulating  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-63638 · Severity: high · CVSS 8.3 · Published 2026-09-18

OpenImageIO is a widely-used image processing library for VFX and animation workflows. A crafted cineon image file with an unsupported bit depth value can trigger a heap buffer overflow when the library processes it, allowing an attacker to corrupt memory and potentially execute arbitrary code on systems that process untrusted image files.

Technologies: [Academy Software Foundation OpenImageIO](https://junglewise.ai/threats/technologies/openimageio). Vendors: [Academy Software Foundation](https://junglewise.ai/threats/vendors/academy-software-foundation).

## Quick answers

**Is CVE-2026-63638 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63638 being exploited in the wild.

**How severe is CVE-2026-63638?** High severity, with a CVSS score of 8.3, published 18 September 2026.

**Which products and versions are affected?** Academy Software Foundation OpenImageIO prior to 3.0.21.0, 3.1.16.0, and 3.2.0.3-beta1.

**Is there a fix for CVE-2026-63638?** A patch was published on 2026-07-06: Fix merged in commit 6f2b2e8 to validate bit depth against libcineon's supported set Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-63638 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-63638?** Check whether you run Academy Software Foundation OpenImageIO at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A mismatch between OpenImageIO's bit-depth validation (accepting 1–32) and libcineon's supported depths (only 8, 10, 12, 16, 32, 64) allows a crafted cineon file with an unsupported depth like 26 to pass initial checks and cause a heap out-of-bounds write in CineonInput::read_native_scanline(), when attacker-controlled data is written beyond the caller-allocated 4-byte-per-pixel buffer. The fix tightens validation to reject unsupported bit depths before calling the vulnerable libcineon code.

## Affected products

- Academy Software Foundation OpenImageIO prior to 3.0.21.0, 3.1.16.0, and 3.2.0.3-beta1

## Timeline

- 2026-09-18: disclosed: CVE-2026-63638 published
- 2026-07-06: patched: Fix merged in commit 6f2b2e8 to validate bit depth against libcineon's supported set

## References

- [https://github.com/AcademySoftwareFoundation/OpenImageIO/commit/6f2b2e85b3b3933ccc5a46303d5535f99bfa39fb](https://github.com/AcademySoftwareFoundation/OpenImageIO/commit/6f2b2e85b3b3933ccc5a46303d5535f99bfa39fb)
- [https://github.com/AcademySoftwareFoundation/OpenImageIO/pull/5283](https://github.com/AcademySoftwareFoundation/OpenImageIO/pull/5283)

## Related threats

- [OpenImageIO integer overflow in Cineon codec scanline buffer](https://junglewise.ai/threats/cve-2026-113681-openimageio-before-3-0-20-0-3-1-x-before-3-1-15-0-and-3-2-x)
- [OpenImageIO heap overflow in TIFF CMYK decoding](https://junglewise.ai/threats/cve-2026-67549-openimageio-is-a-toolset-for-reading-writing-and-manipulating)
- [OpenImageIO use-after-scope in multithreaded TIFF decompression](https://junglewise.ai/threats/cve-2026-65970-openimageio-is-a-toolset-for-reading-writing-and-manipulating)
- [OpenImageIO integer overflow in GIF palette splitting](https://junglewise.ai/threats/cve-2026-65969-openimageio-is-a-toolset-for-reading-writing-and-manipulating)
- [OpenImageIO out-of-bounds read in PSD parser](https://junglewise.ai/threats/cve-2026-63635-openimageio-is-a-toolset-for-reading-writing-and-manipulating)