CVE-2026-26200 HDFGroup CVE debrief

Who should care

Organizations using HDF5 versions prior to 1.14.4-2 should prioritize patching this vulnerability to prevent potential exploitation. This vulnerability may be of particular interest to organizations in industries that rely heavily on data management, such as scientific research, finance, and healthcare. Additionally, security teams and vulnerability management teams should be aware of this vulnerability and take steps to identify and patch affected systems.

Technical summary

CVE-2026-26200 is a write-based heap buffer overflow vulnerability in HDF5. An attacker who can control an `h5` file parsed by HDF5 can trigger this vulnerability. The vulnerability is caused by a lack of proper validation of user-input data, allowing an attacker to write arbitrary data to the heap. This can lead to a denial-of-service condition and potentially remote code execution. The vulnerability is fixed in version 1.14.4-2, which includes improved validation of user-input data.

Defensive priority

High priority should be given to patching this vulnerability, as it has a high CVSS score and could potentially lead to remote code execution. Organizations should prioritize patching systems that are most likely to be targeted by attackers.

Recommended defensive actions

• Patch HDF5 to version 1.14.4-2 or later
• Review and update vulnerability management processes to ensure timely patching of high-severity vulnerabilities
• Conduct a thorough inventory of systems using HDF5 and prioritize patching based on risk and likelihood of exploitation
• Implement compensating controls, such as monitoring and intrusion detection, to detect potential exploitation attempts
• Consider implementing additional security measures, such as data loss prevention and access controls, to protect sensitive data

Evidence notes

The CVE-2026-26200 vulnerability was publicly disclosed on February 19, 2026, and has since been modified on June 30, 2026. The vulnerability has a CVSS score of 7.8 and is considered high-severity. The vulnerability is caused by a write-based heap buffer overflow condition in HDF5, which can be triggered by an attacker who can control an `h5` file parsed by HDF5.

Official resources