How severe is CVE-2026-34378?

CVE-2026-34378 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-34378 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34378?

CVE-2026-34378 affects Openexr. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34378?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-34378 have an EU (EUVD) identifier?

Yes. CVE-2026-34378 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19303.

When was CVE-2026-34378 published?

CVE-2026-34378 was published on 2026-04-06 and last updated on 2026-06-17.

CVE-2026-34378

CVE-2026-34378 is a medium-severity vulnerability in Openexr with a CVSS 3.x base score of 6.5. 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

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19303
Weakness: CWE-190
Affected product: Openexr
Published: 2026-04-06
Last modified: 2026-06-17

Description

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.4.0 to before 3.4.9, a missing bounds check on the dataWindow attribute in EXR file headers allows an attacker to trigger a signed integer overflow in generic_unpack(). By setting dataWindow.min.x to a large negative value, OpenEXRCore computes an enormous image width, which is later used in a signed integer multiplication that overflows, causing the process to terminate with SIGILL via UBSan. This vulnerability is fixed in 3.4.9.

Frequently asked questions

What is CVE-2026-34378?: OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.4.0 to before 3.4.9, a missing bounds check on the dataWindow attribute in EXR file headers allows an attacker to trigger a signed integer overflow in generic_unpack(). By setting dataWindow.min.x to a large negative value, OpenEXRCore computes an enormous image width, which is later used in a signed integer multiplication that overflows, causing the process to terminate with SIGILL via UBSan. This vulnerability is fixed in 3.4.9.
How severe is CVE-2026-34378?: CVE-2026-34378 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-34378 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34378?: CVE-2026-34378 affects Openexr. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34378?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-34378 have an EU (EUVD) identifier?: Yes. CVE-2026-34378 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19303.
When was CVE-2026-34378 published?: CVE-2026-34378 was published on 2026-04-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:openexr:openexr:*:*:*:*:*:*:*:*

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