CVE-2026-26200: HDF5 Affected by H5T__conv_struct_opt Heap Buffer Overflow

Vulnerability summary

CVE-2026-26200 is a high (CVSS 7.8) Heap-based Buffer Overflow vulnerability in hdfgroup hdf5. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 36.2% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 19-02-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

Description

HDF5 is software for managing data. Prior to version 1.14.4-2, an attacker who can control an `h5` file parsed by HDF5 can trigger a write-based heap buffer overflow condition. This can lead to a denial-of-service condition, and potentially further issues such as remote code execution depending on the practical exploitability of the heap overflow against modern operating systems. Real-world exploitability of this issue in terms of remote-code execution is currently unknown. Version 1.14.4-2 fixes the issue.

• CWE-122Heap-based Buffer OverflowThe product writes past the end of a buffer that was allocated on the heap.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer.