CVE-2026-59187 in OpenEXR
Summary
by MITRE • 08/25/2026
OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. OpenEXR versions 3.3.0 through 3.3.12 and 3.4.0 through 3.4.13 are vulnerable to a heap out-of-bounds write when exrmetrics reads a crafted deep scanline EXR. This occurs with pixel conversion options such as --pixelmode float or --bench because DeepSlice requests FLOAT output while the backing sample buffers are allocated using the input HALF element size. The 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 for the EXR image format, a standard deeply entrenched in the motion picture industry due to its support for high dynamic range imaging and complex data structures like deep images. The vulnerability identified affects specific versions of this library, namely 3.3.0 through 3.3.12 and 3.4.0 through 3.4.13. This security flaw manifests as a heap out-of-bounds write when the exrmetrics utility processes a maliciously crafted deep scanline EXR file under specific pixel conversion conditions, such as using the --pixelmode float or --bench flags. The core technical issue arises from a mismatch in memory allocation logic during data type conversion operations. Specifically, when DeepSlice requests output in FLOAT format, the system allocates backing sample buffers based on the size of HALF elements rather than adjusting for the larger FLOAT element size required by the target format.
This discrepancy leads to insufficient buffer allocation relative to the actual amount of data being written during the conversion process. As a result, subsequent write operations exceed the boundaries of the allocated heap memory region. Heap out-of-bounds writes are particularly dangerous because they can corrupt adjacent memory structures, potentially leading to application crashes or denial of service conditions in stable environments. In more severe scenarios involving carefully crafted payloads, such memory corruption can be exploited to achieve arbitrary code execution by overwriting function pointers or other critical control data within the heap metadata. This aligns with Common Weakness Enumeration CWE-787, which classifies out-of-bounds writes as a significant integrity violation that compromises the stability and security of software systems.
The operational impact is primarily observed when users invoke exrmetrics on untrusted deep scanline EXR files while specifying float output modes. Since exrmetrics is often used for benchmarking or analyzing image properties, it may be run in automated pipelines where input sources are not fully vetted. An attacker could distribute a maliciously constructed EXR file that triggers this vulnerability upon processing by an unsuspecting user or service utilizing the affected versions of OpenEXR. This represents a classic case of improper memory management during type conversion, highlighting the risks associated with deep image formats that involve complex internal data structures and variable element sizes.
To mitigate this risk, organizations relying on OpenEXR must ensure they upgrade to version 3.3.13 or later for the 3.3 branch, or version 3.4.14 and above for the 3.4 branch. These updated releases contain fixes that correctly allocate buffer sizes based on the output data type rather than the input type during deep slice conversions. Additionally, defensive coding practices such as rigorous bounds checking before memory writes should be enforced in any custom implementations of EXR parsing logic. From a threat intelligence perspective, this vulnerability can be mapped to MITRE ATT&CK techniques related to exploitation for privilege escalation or denial of service via buffer overflow mechanisms, specifically emphasizing the importance of validating input data structures against expected memory layouts during format-specific processing tasks.