CVE-2026-34379 OpenEXR has a misaligned write in LossyDctDecoder_execute leading to undefined behavior (DWA/DWAB decompression)
A misaligned memory write in OpenEXR's DWA decoder can cause crashes or potential code execution when processing malicious EXR files.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-34379?
CVE-2026-34379 is a high-severity memory corruption vulnerability in Openexr Openexr, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
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.
Which versions are affected by CVE-2026-34379?
It affects 1 product.
Products include Openexr Openexr.
How do I fix CVE-2026-34379?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-34379 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34379 exists.
Other vulnerabilities in Openexr Openexr
- CVE-2023-5841 OpenEXR Heap Overflow in Scanline Deep Data Parsing
- CVE-2026-41142 OpenEXR is Vulnerable to Integer overflow in ImageChannel::resize leads to heap OOB write via OpenEXRUtil public API
- CVE-2026-42216 OpenEXR: Out-of-bounds read in `IDManifest::init()` during prefix expansion
- CVE-2017-9111 OpenEXR invalid write
- CVE-2017-9113 Memory corruption in n/a
Sources
Also known as BELL-CVE-2026-34379, DEBIAN-CVE-2026-34379, GHSA-w88v-vqhq-5p24, JLSEC-2026-143, ROOT-OS-DEBIAN-11-CVE-2026-34379, ROOT-OS-DEBIAN-12-CVE-2026-34379 and 2 more.