CVE-2026-68514 in OpenEXR
Summary
by MITRE • 08/25/2026
OpenEXR is the reference implementation and specification for the EXR image file format, widely used in the motion picture industry. In versions 3.3.0 through 3.3.12 and 3.4.0 through 3.4.13, the PyOpenEXR Python bindings contain a heap out-of-bounds write triggered when reading a crafted deep scanline EXR file. When a deep file declares a literal channel named left alongside layer-prefixed RGB channels left.R, left.G, and left.B, the wrapper processes the literal left channel first and allocates a scalar deep sample array for it, then reuses that same array as the coalesced destination for the prefixed RGB group. The deep reader registers sample slices with an RGB stride (three lanes) into storage that was allocated with scalar shape, so decoding the deep samples writes past the allocation. Opening such a file through the default public Python API, OpenEXR.File(path), causes a heap buffer overflow during normal deep sample decode, leading to memory corruption and a crash. This issue is fixed in versions 3.3.13 and 3.4.14.
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Analysis
by VulDB Data Team • 08/25/2026
OpenEXR serves as the reference implementation and specification for the EXR image file format, which has become an industry standard within the motion picture sector due to its support for high dynamic range imaging and complex data structures. The PyOpenEXR Python bindings provide a critical interface for developers working with these files in automated pipelines or analysis tools. In versions 3.3.0 through 3.3.12 and 3.4.0 through 3.4.13, a significant memory safety vulnerability exists within the deep scanline decoding logic of this library. This flaw manifests as a heap out-of-bounds write, which occurs when processing specifically crafted EXR files that exploit inconsistencies in channel naming conventions and array allocation strategies.
The technical root cause lies in how the wrapper handles literal channels versus layer-prefixed channels during the parsing of deep scanline data. When an openEXR file declares both a literal channel named left and separate RGB channels prefixed with the same name, such as left.R, left.G, and left.B, the decoder exhibits flawed logic regarding memory allocation and reuse. The system first processes the literal left channel and allocates a scalar deep sample array to hold its data. Subsequently, when processing the grouped RGB channels, the code incorrectly reuses this previously allocated scalar array as the destination for coalescing the three-component color data. This logical error ignores the dimensional mismatch between the source data and the target buffer.
During the decoding of deep samples, the reader registers sample slices with an RGB stride, indicating that each element consists of three lanes or components. However, because the underlying storage was allocated based on a scalar shape intended for single-component values, writing multi-lane data into this space results in writes extending beyond the bounds of the allocated heap memory. This condition constitutes a classic heap buffer overflow vulnerability. The impact is severe, as opening such a maliciously crafted file through the default public Python API, specifically OpenEXR.File(path), triggers immediate memory corruption. In most execution environments, this leads to application crashes and potential denial-of-service conditions for services relying on image processing.
From a security classification perspective, this vulnerability aligns with CWE-787: Out-of-bounds Write, as it involves writing data beyond the allocated buffer boundaries. It also relates to CWE-120: Buffer Copy without Checking Size of Input in C/C++, reflecting the failure to verify that the destination array can accommodate the stride-based input data. In terms of adversary behavior, this flaw could be leveraged within ATT&CK technique T1496: Resource Hijacking if used for denial-of-service, or potentially as a primitive for further exploitation leading to arbitrary code execution depending on the memory layout and exploitability context in specific deployment scenarios.
The vulnerability is effectively mitigated by upgrading to patched versions of the library. Specifically, version 3.3.13 and version 3.4.14 contain fixes that correct the allocation logic to ensure that buffers are sized appropriately for their intended stride and data type. Organizations utilizing PyOpenEXR should prioritize updating to these safe versions to prevent memory corruption issues arising from malformed or maliciously constructed EXR files in production environments.