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CVE-2026-34588 — openexr

CVE-2026-34588 is a Out-of-bounds Read vulnerability in openexr. A fix is available for openexr — see the affected versions and patch details below.

OpenEXR has a signed 32-bit Overflow in PIZ Decoder Leads to OOB Read/Write

Also known asGHSA-588r-cr5c-w6hfPYSEC-2026-2845
Published
Apr 6, 2026
Updated
Sep 18, 2026
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34588.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs41th percentile — riskier than 41% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

3 pkgs affected
🐍openexr🐍openexr🐍openexr

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.1.0 to before 3.2.7, 3.3.9, and 3.4.9, internal_exr_undo_piz() advances the working wavelet pointer with signed 32-bit arithmetic. Because nx, ny, and wcount are int, a crafted EXR file can make this product overflow and wrap. The next channel then decodes from an incorrect address. The wavelet decode path operates in place, so this yields both out-of-bounds reads and out-of-bounds writes. This vulnerability is fixed in 3.2.7, 3.3.9, and 3.4.9.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIopenexr≥ 3.1.0&&< 3.2.73.2.7pip install --upgrade 'openexr==3.2.7'
🐍PyPIopenexr≥ 3.3.0&&< 3.3.93.3.9pip install --upgrade 'openexr==3.3.9'
🐍PyPIopenexr≥ 3.4.0&&< 3.4.93.4.9pip install --upgrade 'openexr==3.4.9'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openexr, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update openexr to 3.2.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34588 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34588 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-34588. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
ProductFixed inAdvisory
Red Hat Enterprise Linux 10openexr-0:3.1.10-8.el10_1.2RHSA-2026:15888
Red Hat Enterprise Linux 10openexr-0:3.1.10-8.el10_2.2RHSA-2026:19146
Red Hat Enterprise Linux 10.0 Extended Update Supportopenexr-0:3.1.10-8.el10_0.2RHSA-2026:17656
Red Hat Enterprise Linux 9openexr-0:3.1.1-3.el9_7.2RHSA-2026:15887
Red Hat Enterprise Linux 9openexr-0:3.1.1-3.el9_8.2RHSA-2026:19359
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutionsopenexr-0:3.1.1-2.el9_0.3RHSA-2026:19587
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutionsopenexr-0:3.1.1-2.el9_2.3RHSA-2026:17659
Red Hat Enterprise Linux 9.4 Extended Update Supportopenexr-0:3.1.1-2.el9_4.3RHSA-2026:17658
UbuntuHIGH
USN-8259-1Ubuntu

Frequently Asked Questions

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.1.0 to before 3.2.7, 3.3.9, and 3.4.9, internal_exr_undo_piz() advances the working wavelet pointer with signed 32-bit arithmetic. Because nx, ny, and wcount are int, a crafted EXR file can make this product overflow and wrap. The next channel then decodes from an incorrect address. The wavelet decode path operates in place, so this yields both out-of-bounds reads and out-of-bounds writes. This vulnerability is fixed in 3.2.7, 3.3.9, and 3.4.9.
O3 Security · Impact-Aware SCA

Is CVE-2026-34588 in your dependencies?

O3 Security finds CVE-2026-34588 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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CVE-2026-34588: openexr Memory Corruption | O3 Security