CVE-2026-34544
CVE-2026-34544 is a CWE-190 vulnerability in openexr. O3 Security confirms whether CVE-2026-34544 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
OpenEXR: integer overflow to OOB write in uncompress_b44_impl()
Blast Radius
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 | 3.4.8 |
| 🐍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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether CVE-2026-34544 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
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 detects CVE-2026-34544 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.