CVE-2026-34378: OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma

Routine

MEDIUM 6.5UPGRADE

CVE-2026-34378 is a medium-severity flaw (CVSS 6.5) affecting openexr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 sig

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-190
Published	2026-04-06
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: openexr

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-06 16:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

openexr openexr UPGRADE

Affected: >= 3.4.0 and < 3.4.9

Fixed in: 3.4.9

Safe to downgrade to: a release before 3.4.0

1. Check installed version

apt-cache policy openexr || rpm -q openexr || openexr --version

2. UPGRADE to 3.4.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openexr

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openexr

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.4.0 (Debian / Ubuntu)

apt-cache madison openexr sudo apt install openexr=<VERSION_BEFORE_3.4.0> sudo apt-mark hold openexr

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openexr sudo dnf downgrade openexr-<VERSION_BEFORE_3.4.0> sudo dnf versionlock add openexr

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34378?

openexr: upgrade to 3.4.9. Exact commands for each OS are on this page.

Is CVE-2026-34378 being exploited?

CVE-2026-34378 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34378 affect?

CVE-2026-34378 affects openexr. Severity is medium (CVSS 6.5). 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 head

How urgent is CVE-2026-34378?

Priority 32/100. Public exploit reference

Related CVEs

CVE-2026-34545 HIGH 7.3 UPGRADE OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma
CVE-2026-34588 HIGH 7.8 UPGRADE OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma
CVE-2026-34379 HIGH 7.1 UPGRADE OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma
CVE-2026-39886 MEDIUM 5.3 UPGRADE OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma
CVE-2026-34589 MEDIUM 5.0 UPGRADE OpenEXR provides the specification and reference implementation of the EXR file format, an image storage forma

References

← Back to latest CVEs