CVE-2026-19029 Overview
CVE-2026-19029 is a heap-based buffer over-read [CWE-125] in the H5Z__filter_scaleoffset() function located in src/H5Zscaleoffset.c. The flaw affects HDF5 through version 2.2.0. A crafted HDF5 file triggers an out-of-bounds read when the stored minimum bits value equals the full precision of the datatype. The decoder copies d_nelmts * size bytes from the compressed chunk without verifying the chunk actually contains that many bytes. Both inputs originate from attacker-controlled scale-offset filter parameters stored in the dataset's filter pipeline message. Successful exploitation causes a denial of service through application crash.
Critical Impact
An attacker who supplies a malicious HDF5 file can crash any application that parses it using the vulnerable HDF5 library, disrupting scientific computing and data analysis workflows.
Affected Products
- HDF5 library versions through 2.2.0
- Applications linking against vulnerable HDF5 releases
- Scientific computing pipelines consuming untrusted HDF5 files
Discovery Timeline
- 2026-10-06 - CVE-2026-19029 published to NVD
- 2026-10-07 - Last updated in NVD database
Technical Details for CVE-2026-19029
Vulnerability Analysis
The vulnerability resides in the scale-offset filter decoder of HDF5, a widely used library for storing and managing hierarchical scientific data. The H5Z__filter_scaleoffset() function processes compressed chunks whose parameters are supplied through the dataset's filter pipeline message. When the stored minimum-bits parameter matches the full precision of the datatype, the decoder enters a code path that performs a raw byte copy of d_nelmts * size bytes directly from the compressed chunk buffer. The function omits a bounds check that would confirm the chunk actually holds the requested number of bytes. Reading past the end of the heap allocation triggers a crash, producing a denial of service condition in any process consuming the malicious file.
Root Cause
The root cause is missing input validation in the scale-offset decoder. Two attacker-controlled values, d_nelmts and size, feed directly into a memory copy without verifying that their product remains within the compressed chunk's actual length. Both values are parsed from the filter pipeline message, which is untrusted when the HDF5 file originates from an external source.
Attack Vector
The attack requires local file access and user interaction. An attacker crafts an HDF5 file that specifies a scale-offset filter with a minimum-bits value equal to the datatype's full precision, combined with an inflated d_nelmts or size. The victim opens or processes the file with a vulnerable HDF5-based application, and the decoder reads beyond the allocated chunk buffer. The result is an application crash. The vulnerability does not grant code execution or data confidentiality impact based on available analysis.
The H5Z__filter_scaleoffset() function performs the unchecked copy during chunk decoding. See the HDF5 Pull Request 6718 for the upstream fix and technical analysis.
Detection Methods for CVE-2026-19029
Indicators of Compromise
- Unexpected crashes or segmentation faults in applications parsing HDF5 files
- HDF5 files from untrusted sources containing scale-offset filter entries in the filter pipeline message
- Core dumps referencing H5Z__filter_scaleoffset or H5Zscaleoffset.c in the backtrace
Detection Strategies
- Scan HDF5 files with h5dump or h5ls in a sandboxed environment to flag abnormal scale-offset filter parameters
- Monitor process telemetry for repeated crashes of analytics, visualization, or scientific tooling that links the HDF5 library
- Review software bills of materials to identify applications bundling HDF5 versions at or below 2.2.0
Monitoring Recommendations
- Alert on crash events whose stack traces include HDF5 filter decoding functions
- Log file ingestion pipelines that process HDF5 inputs from external collaborators or public datasets
- Track HDF5 library version inventory across research, HPC, and data-science hosts
How to Mitigate CVE-2026-19029
Immediate Actions Required
- Inventory all applications and container images that bundle HDF5 2.2.0 or earlier
- Restrict ingestion of HDF5 files to trusted sources until patched builds are deployed
- Process untrusted HDF5 files inside isolated sandboxes or ephemeral containers
Patch Information
The upstream fix is tracked in HDF5 Pull Request 6718. Rebuild downstream applications against a patched HDF5 release once available, and redistribute updated binaries to all affected hosts.
Workarounds
- Reject HDF5 files whose filter pipeline messages advertise scale-offset filters with suspicious d_nelmts or size values
- Run HDF5 parsing workloads under process isolation with resource limits and automatic restart
- Disable or remove the scale-offset filter in build configurations where it is not required
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
