CVE-2026-34378 OpenEXR has a signed integer overflow in generic_unpack() when parsing EXR files with crafted negative dataWindow.min.x
An attacker can cause a denial of service by crafting an EXR file with a negative dataWindow value, triggering an integer overflow in OpenEXR.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-34378?
CVE-2026-34378 is a medium-severity vulnerability in Openexr Openexr, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-190
Which versions are affected by CVE-2026-34378?
It affects 1 product.
Products include Openexr Openexr.
How do I fix CVE-2026-34378?
Upgrade to a fixed version.
Is CVE-2026-34378 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34378 exists.
Other vulnerabilities in Openexr Openexr
- CVE-2023-5841 OpenEXR Heap Overflow in Scanline Deep Data Parsing
- CVE-2026-41142 OpenEXR is Vulnerable to Integer overflow in ImageChannel::resize leads to heap OOB write via OpenEXRUtil public API
- CVE-2026-42216 OpenEXR: Out-of-bounds read in `IDManifest::init()` during prefix expansion
- CVE-2017-9111 OpenEXR invalid write
- CVE-2017-9113 Memory corruption in n/a
Sources
Also known as BELL-CVE-2026-34378, DEBIAN-CVE-2026-34378, GHSA-v76p-4qvv-vh4g, JLSEC-2026-142, UBUNTU-CVE-2026-34378.