Vulnerability · Published Apr 6, 2026 · Assigned by GitHub_M
CVE-2026-34379OpenEXR has a misaligned write in LossyDctDecoder_execute leading to undefined behavior (DWA/DWAB decompression)
High 7.1
In plain English
A high-severity out-of-bounds write in openexr from AcademySoftwareFoundation. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
OpenEXR provides the specification and reference implementation of the EXR file format, an image storage format for the motion picture industry. From 3.2.0 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.22 | openexr | 3.3.11-r0 | ALPINE-CVE-2026-34379 |
| Alpine:v3.23 | openexr | 3.4.13-r0 | ALPINE-CVE-2026-34379 |
| Alpine:v3.24 | openexr | 3.4.10-r0 | ALPINE-CVE-2026-34379 |
| Debian:12 | openexr | no fix listed | DEBIAN-CVE-2026-34379 |
| Debian:13 | openexr | no fix listed | DEBIAN-CVE-2026-34379 |
| Debian:14 | openexr | 3.4.14-0.1 | DEBIAN-CVE-2026-34379 |
| Ubuntu:26.10 | openexr | no fix listed | UBUNTU-CVE-2026-34379 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AcademySoftwareFoundation | openexr | >= 3.2.0, < 3.2.7>= 3.3.0, < 3.3.9>= 3.4.0, < 3.4.9 |
Weakness: CWE-704, CWE-787, CWE-843, CWE-475 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
References
- https://github.com/AcademySoftwareFoundation/openexr/security/advisories/GHSA-w88v-vqhq-5p24 x_refsource_CONFIRM
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.2.7 x_refsource_MISC
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.3.9 x_refsource_MISC
- https://github.com/AcademySoftwareFoundation/openexr/releases/tag/v3.4.9 x_refsource_MISC
- https://access.redhat.com/security/cve/CVE-2026-34379 vdb-entry, x_refsource_REDHAT
- RHBZ#2455402 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34379.json x_sadp-csaf-vex