CVE-2026-26197 HDFGroup CVE debrief

Who should care

Users of the HDF5 library and applications that process HDF5 files should be aware of this vulnerability. This vulnerability may be relevant to organizations that handle large datasets or use HDF5 for data storage. IT teams responsible for data storage and processing, security teams monitoring for potential threats, and developers using the HDF5 library in their applications should prioritize addressing this vulnerability.

Technical summary

The HDF5 library has a vulnerability that can be triggered by a corrupted file. Specifically, if the size, number of elements, and element size of an array datatype are not in agreement, an out of bounds read can occur. This is because the full size of the datatype, number of elements, and element size are stored separately. If any of these values are corrupted, it can lead to an out of bounds read. The vulnerability is only present in maliciously altered files. No exploit details are publicly available.

Defensive priority

Medium

Recommended defensive actions

• Review and update HDF5 library to the latest version
• Validate and sanitize HDF5 files before processing
• Implement bounds checking when reading HDF5 files
• Monitor for suspicious HDF5 file activity
• Perform vulnerability scanning on systems that process HDF5 files
• Review system logs for signs of potential exploitation
• Isolate systems that process HDF5 files from critical networks

Evidence notes

The CVE record and NVD detail provide information about the vulnerability in HDF5, a high-performance library and file format specification. The vulnerability can be triggered by a corrupted file where an array datatype's size, the number of elements, and the element size are not in agreement, leading to an out of bounds read. This occurs because the array datatype stores the full size of the datatype separately from the number of elements and the element size. The vulnerability is present only in files that have been maliciously altered. Users should validate and sanitize HDF5 files before processing and implement bounds checking when reading HDF5 files. Evidence is limited to CVE and NVD details, with no additional context from other sources.

Official resources