{"id":"CVE-2026-19027","title":"The H5Z__nbit_decompress_one_byte, H5Z__nbit_decompress_one_nooptype, and H5Z__nbit_decompress_one_atomic functions in H5Znbit.c in HDF5\nprior to 2.3.0 advance a read index into the compressed chunk buffer without bounding it against the…","summary":"The H5Z__nbit_decompress_one_byte, H5Z__nbit_decompress_one_nooptype, and H5Z__nbit_decompress_one_atomic functions in H5Znbit.c in HDF5\nprior to 2.3.0 advance a read index into the compressed chunk buffer without bounding it against the…","severity":"medium","cvss":6.9,"cvssVector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","cwe":["CWE-125"],"vendor":"The HDF Group","product":"HDF5","affected":["HDF5 <=2.3.0"],"published":"2026-08-06","updated":"2026-10-06","sourceUpdated":"2026-10-06T21:17:20.120","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-19027","references":[{"url":"https://github.com/HDFGroup/hdf5/issues/6489","label":"0253b833-3e77-4dfe-9d57-17db1a2f0a74"},{"url":"https://github.com/HDFGroup/hdf5/issues/6492","label":"0253b833-3e77-4dfe-9d57-17db1a2f0a74"},{"url":"https://github.com/HDFGroup/hdf5/pull/6497","label":"0253b833-3e77-4dfe-9d57-17db1a2f0a74"},{"url":"https://github.com/HDFGroup/hdf5/issues/6489","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-06T14:29:51.698432Z"},"cvssSource":"cna","epss":0.0018,"epssPercentile":0.06958,"ingestedAt":"2026-10-06T21:20:28.947Z","slug":"CVE-2026-19027","body":"## Overview\n\nThe H5Z__nbit_decompress_one_byte, H5Z__nbit_decompress_one_nooptype, and H5Z__nbit_decompress_one_atomic functions in H5Znbit.c in HDF5\nprior to 2.3.0 advance a read index into the compressed chunk buffer without bounding it against the buffer's actual size. This allows attackers to cause an out-of-bounds heap read, and in constrained cases disclosure of adjacent heap memory into decompressed dataset values, via a crafted HDF5 file whose N-Bit filter parameters describe more decompressed data than the stored compressed chunk actually contains, triggered via H5Dread, e.g. by the h5ls or h5repack tools.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":50,"depthScoreParts":{"impact":38,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[]}