CVE-2026-34544 — openexr
Fix: AcademySoftwareFoundation/openexr@35e7aa3CVE-2026-34544 is a CWE-190 vulnerability in openexr. A fix is available for openexr — see the affected versions and patch details below.
OpenEXR: integer overflow to OOB write in uncompress_b44_impl()
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34544.
EPSS Exploitation Probability
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
openexr🐍openexr🐍openexrReal-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 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | openexr | ≥ 3.4.0&&< 3.4.8 | 3.4.8pip install --upgrade 'openexr==3.4.8' |
| 🐍PyPI | openexr | ≥ 3.3.0 | No fix |
| 🐍PyPI | openexr | ≥ 3.2.0 | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update openexr to 3.4.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34544 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34544 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34544. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34544 in your dependencies?
O3 Security finds CVE-2026-34544 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.