OpenEXR has a misaligned write in LossyDctDecoder_execute leading to undefined behavior (DWA/DWAB decompression)

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Summary

CVECVE-2026-34379
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-06 16:16:35 UTC
Updated2026-04-07 19:04:50 UTC
DescriptionOpenEXR 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

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

EPSS: 0.000330000 probability, percentile 0.095690000 (date 2026-04-07)

Problem Types: CWE-704 | CWE-787 | CWE-843 | CWE-704 CWE-704: Incorrect Type Conversion or Cast | CWE-787 CWE-787: Out-of-bounds Write | CWE-843 CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Openexr Openexr All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA AcademySoftwareFoundation Openexr affected >= 3.2.0, < 3.2.7 Not specified
CNA AcademySoftwareFoundation Openexr affected >= 3.3.0, < 3.3.9 Not specified
CNA AcademySoftwareFoundation Openexr affected >= 3.4.0, < 3.4.9 Not specified

References

ReferenceSourceLinkTags
github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.2.7 [email protected] github.com Product, Release Notes
github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.3.9 [email protected] github.com Product, Release Notes
github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.9 [email protected] github.com Product, Release Notes
github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-w8... [email protected] github.com Exploit, Vendor Advisory
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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