CVE-2026-34380

CVE-2026-34380 is a medium-severity vulnerability in Openexr with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Description

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.

Frequently asked questions

What is CVE-2026-34380?
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.
How severe is CVE-2026-34380?
CVE-2026-34380 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2026-34380 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34380?
CVE-2026-34380 affects Openexr. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34380?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-34380 have an EU (EUVD) identifier?
Yes. CVE-2026-34380 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19307.
When was CVE-2026-34380 published?
CVE-2026-34380 was published on 2026-04-06 and last updated on 2026-06-17.

References

Affected products (1)

More vulnerabilities in Openexr

All CVEs affecting Openexr →

Other CWE-190 (Integer Overflow or Wraparound) vulnerabilities

Browse all CWE-190 (Integer Overflow or Wraparound) vulnerabilities →