# CVE-2026-63638: OpenImageIO: Cineon invalid bit depth heap out-of-bounds write

> A crafted Cineon image triggers a heap out-of-bounds write in OpenImageIO, potentially allowing code execution or denial of service.

- **Severity:** High 8.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-63638, GHSA-9hxv-jvgr-3x8g, UBUNTU-CVE-2026-63638

## What is CVE-2026-63638?

CVE-2026-63638 is a high-severity memory corruption vulnerability in Openimageio Openimageio, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, 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 3.0.21.0, 3.1.16.0, and 3.2.0.3-beta1, A crafted cineon image can declare unsupported component bit depth 26. cineoninput::open() maps it to a 32-bit imagespec, but libcineon maps the unsupported depth to an 8-byte value, so cineoninput::read_native_scanline() causes attacker-controlled data to be written beyond the 4-byte-per-pixel caller buffer, resulting in a heap out-of-bounds write and memory corruption. The affected implementation is identified by src/cineon.imageio/cineoninput.cpp, CineonInput::open(), CineonInput::read_native_scanline(), ComponentDataSize(), bit depth 26, and ImageSpec, which define the relevant source path, functions, state, and trigger. This issue is fixed in versions 3.0.21.0, 3.1.16.0, and 3.2.0.3-beta1.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-63638?

It affects 1 product.


Products: Openimageio Openimageio.

## How do I fix CVE-2026-63638?

Upgrade to a fixed version.

## Is CVE-2026-63638 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63638 exists.

## Other vulnerabilities in Openimageio Openimageio

- [CVE-2024-55192](https://insights.sbomify.com/CVE-2024-55192/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-55194](https://insights.sbomify.com/CVE-2024-55194/): Memory corruption in n/a (critical 9.8)
- [CVE-2023-42299](https://insights.sbomify.com/CVE-2023-42299/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-38143](https://insights.sbomify.com/CVE-2022-38143/): Memory corruption in OpenImageIO (critical 9.8)
- [CVE-2026-43908](https://insights.sbomify.com/CVE-2026-43908/): OpenImageIO: Signed integer overflow in ConvertCbYCrYToRGB leads to heap out-of-bounds write in DPX 4:2:2 decoder (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63638 and fix it if it is affected.

What it is: CVE-2026-63638 is a high-severity memory corruption vulnerability in Openimageio Openimageio, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63638 exists.

Affected product: Openimageio Openimageio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63638/ (Markdown: https://insights.sbomify.com/CVE-2026-63638/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63638
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63638
- OSV: https://osv.dev/vulnerability/CVE-2026-63638

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63638/
Summaries are generated and may contain mistakes; the official description above is the record.