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CVE-2026-34378: OpenEXR may crash when opening specially crafted EXR images

CVE-2026-34378 · published 7 months ago

Summary

The OpenEXR library used in Debian and Ubuntu can crash if it reads an image file that contains a maliciously set header value. The problem is fixed in version 3.4.9, so updating OpenEXR to that version or later eliminates the risk.

What to do

Update openexr openexr to version 3.4.9 or later.

Affected software

Ecosystem	Vendor	Product	Affected versions
Debian:14	debian	openexr	All versions
Ubuntu:26.10	canonical	openexr	All versions
–	openexr	openexr	>= 3.4.0, < 3.4.9 `cpe:2.3:a:openexr:openexr::::::::`

Original advisory text

OpenEXR has a signed integer overflow in generic_unpack() when parsing EXR files with crafted negative dataWindow.min.x

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.

References

https://security-tracker.debian.org/tracker/CVE-2026-34378 Vendor Advisory
https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-v7... Exploit Vendor Advisory
https://ubuntu.com/security/CVE-2026-34378 Third Party Advisory
https://www.cve.org/CVERecord?id=CVE-2026-34378 Third Party Advisory
https://github.com/AcademySoftwareFoundation/openexr/pull/2321 Third Party Advisory
https://github.com/AcademySoftwareFoundation/openexr/commit/088859fb6199e56824c4... Third Party Advisory
https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34378... Vendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-34378 Vendor Advisory
https://github.com/AcademySoftwareFoundation/openexr/commit/7a1c64ca74d12bf5f64a... Third Party Advisory
https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.9 Product Release Notes

Fix within

Internet-facing 60 days

Internal At next upgrade

Not known to be exploited
Needs hands-on effort to exploit
Gives an attacker partial control

Severity

6.5 Medium

Exploitation

<1% chance of attack within 30 days

Type

CWE-190Integer Overflow

Timeline

Published6 Apr 2026

Updated3 Nov 2026

First seen6 Apr 2026

Sources

CVE-2026-34378 · NVD

DEBIAN-CVE-2026-34378 · OSV

UBUNTU-CVE-2026-34378 · OSV

CVE-2026-34378 · OSV

GHSA-v76p-4qvv-vh4g · GHSA

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