🛡️ CVE-2026-34379 — openexr

🟠 CVSS 7.1 — High ⚠️ Exploit Public CWE-704 NVD

7.1

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.2.0 to before 3.2.7, 3.3.9, and 3.4.9, a misaligned memory write vulnerability exists in LossyDctDecoder_execute() in src/lib/OpenEXRCore/internal_dwa_decoder.h:749. When decoding a DWA or DWAB-compressed EXR file containing a FLOAT-type channel, the decoder performs an in-place HALF→FLOAT conversion by casting an unaligned uint8_t * row pointer to float * and writing through it. Because the row buffer may not be 4-byte aligned, this constitutes undefined behavior under the C standard and crashes immediately on architectures that enforce alignment (ARM, RISC-V, etc.). On x86 it is silently tolerated at runtime but remains exploitable via compiler optimizations that assume aligned access. This vulnerability is fixed in 3.2.7, 3.3.9, and 3.4.9.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability high.

Weakness class

CVE-2026-34379 is classified as CWE-704: Incorrect Type Conversion or Cast. The product does not correctly convert an object, resource, or structure from one type to a different type.

Affected software

CVE-2026-34379 is recorded against 1 package.

openexr (from 3.4.0 up to 3.4.9)

Timeline and source

Published on 6 April 2026 and last revised on 15 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. Record sourced from NVD.

References

github.com
github.com
github.com
github.com
access.redhat.com
bugzilla.redhat.com
security.access.redhat.com

CVE-2026-34379 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

BellSoft Debian Debian 12 (Root.io)Debian 13 (Root.io)Ubuntu

Details

Severity HIGH

CVSS Score 7.1

CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H

CWE CWE-704

Public Exploit ⚠️ Yes

Source NVD

Published 2026-04-06

Updated 2026-08-11

Modified 2026-07-15

Fix URL N/A

Affected Packages

Software	From version	Fixed in
openexr	3.4.0	3.4.9

References

Product, Release Notes https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.2.7

Product, Release Notes https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.3.9

Product, Release Notes https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.9

Exploit, Vendor Advisory https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-w88v-vqhq-5p24

https://access.redhat.com/security/cve/CVE-2026-34379

https://bugzilla.redhat.com/show_bug.cgi?id=2455402

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34379.json

🔗 NVD 🔗 Mitre

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