Executive brief
OpenEXR is a widely-used library for reading and writing high-dynamic-range (HDR) image files. A vulnerability in the image decoding process causes the library to branch on uninitialized memory values when unpacking pixel data, which can lead to unpredictable behavior, application crashes, or denial of service when processing specially crafted EXR files.
Technical details
The vulnerability is a use-of-uninitialized-memory (CWE-457) issue in the generic_unpack() function within the OpenEXR image decoding pipeline. The root cause is that a per-tile/per-scanline decode scratch buffer allocated via malloc during exr_decoding_run() is not fully initialized before being read, causing conditional branches to depend on uninitialized heap data. The vulnerability is triggered when processing malformed or specially crafted EXR files that do not fully populate the scratch buffer during decompression. An attacker can exploit this by providing a malicious EXR file that, when opened or validated by an application using OpenEXR, causes undefined behavior. The issue affects versions 3.3.0–3.3.5 and 3.4.0–3.4.2, and patches are available in versions 3.3.6 and 3.4.3.
Affected products
- Academy Software Foundation OpenEXR 3.3.0-3.3.5, 3.4.0-3.4.2
Timeline
- 2025-11-08: disclosed
- 2026-04-06: patched: Versions 3.3.6 and 3.4.3 contain fixes