CVE-2026-34380: OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for…
CVE-2026-34380 · Severity: medium · CVSS 5.9 · Published 2026-04-06
OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.2.0 to before 3.2.7, 3.3.9, and 3.4.9, a signed integer overflow exists in undo_pxr24_impl() in src/lib/OpenEXRCore/internal_pxr24.c at line 377. The expression (uint64_t)(w * 3) computes w * 3 as a signed 32-bit integer before casting to uint64_t. When w is large, this multiplication constitutes undefined behavior under the C standard. On tested builds (clang/gcc without sanitizers), two's-complement wraparound commonly occurs, and for specific values of w the wrapped result is a small positive integer, which may allow the subsequent bounds check to pass incorrectly. If the check is bypassed, the decoding loop proceeds to write pixel data through dout, potentially extending far beyond the allocated output buffer. This vulnerability is fixed in 3.2.7, 3.3.9, and 3.4.9.
No. Junglewise Threat Intelligence has no report of CVE-2026-34380 being exploited in the wild.
How severe is CVE-2026-34380?
Medium severity, with a CVSS score of 5.9, published 6 April 2026.
Which products and versions are affected?
Openexr. The advisory does not name versions.
Is there a fix for CVE-2026-34380?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-34380?
Check whether you run Openexr. 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.