# CVE-2026-34544: PYSEC-2026-2847 - OpenEXR: integer overflow to OOB write in uncompress_b44_impl()

Source: https://junglewise.ai/threats/cve-2026-34544-openexr-integer-overflow-to-oob-write-in-uncompress-b44-impl  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-01  
License: CC BY 4.0 with a link back

CVE-2026-34544 · Severity: high · CVSS 7.3 · Published 2026-04-01

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.

Technologies: [Openexr](https://junglewise.ai/threats/technologies/openexr-openexr), [OpenEXR (PyPI)](https://junglewise.ai/threats/technologies/openexr). Vendors: [Openexr](https://junglewise.ai/threats/vendors/openexr), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-34544 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34544 being exploited in the wild.

**How severe is CVE-2026-34544?** High severity, with a CVSS score of 7.3, published 1 April 2026.

**Which products and versions are affected?** OpenEXR (PyPI) ECOSYSTEM:introduced=3.2.0,fixed=3.4.8, ECOSYSTEM:introduced=3.4.0,fixed=3.4.8.

**Is there a fix for CVE-2026-34544?** Yes. OpenEXR (PyPI): upgrade to 3.4.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-34544?** Check whether you run Openexr or OpenEXR (PyPI) 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.

## How to fix

- OpenEXR (PyPI): upgrade to 3.4.8 or later

  ```sh
  pip install "OpenEXR>=3.4.8"
  ```


## Affected products

- Openexr
- OpenEXR (PyPI) ECOSYSTEM:introduced=3.2.0,fixed=3.4.8, ECOSYSTEM:introduced=3.4.0,fixed=3.4.8

## Identifiers

- CVE-2026-34544
- GHSA-h762-rhv3-h25v
- PYSEC-2026-2847

## Related threats

- [PYSEC-2026-2849 - OpenEXR has heap-buffer-overflow via signed integer underflow in ImfContextInit.cpp](https://junglewise.ai/threats/cve-2026-26981-openexr-has-heap-buffer-overflow-via-signed-integer-underflow-in)
- [PYSEC-2026-2844 - OpenEXR has use after free in PyObject_StealAttrString](https://junglewise.ai/threats/cve-2025-64183-openexr-has-use-after-free-in-pyobject-stealattrstring)
- [PYSEC-2026-2851 - OpenEXR has buffer overflow in PyOpenEXR_old's channels() and channel()](https://junglewise.ai/threats/cve-2025-64182-openexr-has-buffer-overflow-in-pyopenexr-old-s-channels-and)
- [PYSEC-2026-2843 - OpenEXR Makes Use of Uninitialized Memory](https://junglewise.ai/threats/cve-2025-64181-openexr-use-of-uninitialized-memory-in-generic-unpack)
- [PYSEC-2026-1748 - OpenEXR ScanLineProcess::run_fill NULL Pointer Write In "reduceMemory" Mode](https://junglewise.ai/threats/cve-2025-48073-openexr-scanlineprocess-run-fill-null-pointer-write-in)