CVE-2026-34378 | OpenEXR has a signed integer overflow in generic_unpack() when parsing EXR files with crafted negative dataWindow.min.x

Exp

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.

Published: 2026-04-06 Last update: 2026-04-07 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-34378 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.05%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-34378

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-34378

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-18 0.03% 0.05% +0.02%
2 2026-04-07 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34378

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-34378

OS Trackers for CVE-2026-34378

vendor priority summary link
alpine — CVE-2026-34378: 1 source package rows (openexr); 3 state rows across 2 repos (3.23-community, edge-community); fixed 0, open 3. https://security.alpinelinux.org/vuln/CVE-2026-34378
debian unimportant CVE-2026-34378 unimportant priority: Debian including 1 source packages (openexr), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-34378
redhat medium — https://access.redhat.com/security/cve/CVE-2026-34378
suse medium CVE-2026-34378 severity moderate: SUSE including 26 source package names (libIex-3_4-33-3.4.9-1.1, libIex-3_4-33-32bit-3.4.9-1.1, …), 81 product×package rows across 19 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (19 product lines)): Known Not Affected 63, Fixed 18. https://www.suse.com/security/cve/CVE-2026-34378/
ubuntu medium CVE-2026-34378 medium priority: Ubuntu including 1 source packages (openexr), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 7. https://ubuntu.com/security/CVE-2026-34378

Affected software / configurations for CVE-2026-34378

Vendor Product Version Raw CPE
openexr openexr >= 3.4.0, < 3.4.9 cpe:2.3:a:openexr:openexr:*:*:*:*:*:*:*:*

References for CVE-2026-34378

cvelogic Threat Intelligence