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CVE-2026-19027— HDF5 out-of-bounds heap read in N-Bit filter decompression

Quick assessment

Affected
The HDF Group HDF5
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

HDF Group hdf5是HDF Group组织的一个支持海量数据存储与管理的文件格式库。 HDF Group hdf5 2.3.0及之前版本存在缓冲区错误漏洞，该漏洞源于H5Znbit.c中函数对压缩块缓冲区读取索引未进行边界限制，攻击者通过特制HDF5文件触发，可能导致越界堆读取和相邻堆内存泄露。

CVSS 6.9 · Medium EPSS 0.18% · P7

Affected Version Matrix 1

VendorProduct Version RangeStatus
The HDF Group HDF5 <=2.3.0 affected
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I. Basic Information for CVE-2026-19027

Vulnerability Information
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Vulnerability Title
HDF5 out-of-bounds heap read in N-Bit filter decompression
Source: CVE Program / CVE List V5
Vulnerability Description
The H5Z__nbit_decompress_one_byte, H5Z__nbit_decompress_one_nooptype, and H5Z__nbit_decompress_one_atomic functions in H5Znbit.c in HDF5 through 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
HDF Group hdf5 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
HDF Group hdf5是HDF Group组织的一个支持海量数据存储与管理的文件格式库。 HDF Group hdf5 2.3.0及之前版本存在缓冲区错误漏洞，该漏洞源于H5Znbit.c中函数对压缩块缓冲区读取索引未进行边界限制，攻击者通过特制HDF5文件触发，可能导致越界堆读取和相邻堆内存泄露。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
The HDF Group HDF5 <=2.3.0 -

II. Public POCs for CVE-2026-19027

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III. Intelligence Information for CVE-2026-19027

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Patches & Fixes for CVE-2026-19027 (1)

Other References for CVE-2026-19027 (2)

Same Patch Batch · The HDF Group · 2026-08-05 · 6 CVEs total

CVE-2026-19024 8.2 HIGH HDF5 H5Pget_fill_value NULL Pointer Dereference via Malformed Fill Value Message
CVE-2026-19023 6.8 MEDIUM HDF5 h5dump Untrusted Pointer Dereference in Binary Output of Variable-Length String Datas
CVE-2026-19025 6.8 MEDIUM HDF5 divide-by-zero (SIGFPE) via mismatched chunk-layout dimensionality and dataspace rank
CVE-2026-19026 6.8 MEDIUM Nbit filter NULL/short parameter-array dereference
CVE-2026-19028 6.8 MEDIUM HDF5 integer underflow in Fletcher32 filter leads to massive out-of-bounds read

IV. Related Vulnerabilities

Same product: HDF5
Same vendor: The HDF Group
Same weakness: CWE-125

V. Comments for CVE-2026-19027

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