Is there a patch available for CVE-2026-26197?

Yes, a patch is available for CVE-2026-26197. Update the affected software to the latest version immediately.

HDF5 CVE-2026-26197

Q: What is the CVSS score of CVE-2026-26197?

CVE-2026-26197 has a CVSS 4.0 base score of 5.9 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.3%.

EUVD-2026-45969 MEDIUM

Out-of-bounds Read (CWE-125)

2026-07-20 GitHub_M

Buffer Overflow Information Disclosure Hdf5

5.9

CVSS 4.0 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

5.9 MEDIUM

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

5.3 MEDIUM

File delivered remotely (AV:N) but requires crafted input and victim action (AC:H, UI:R); availability-only crash impact with no auth prerequisite (PR:N, C:N, I:N).

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H

4.0 AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE

6.5 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Red Hat

5.3 MEDIUM

qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Analysis Generated

Jul 20, 2026 - 18:12 vuln.today

Patch available

Jul 20, 2026 - 17:02 EUVD

DescriptionCVE.org

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If a file is corrupted such that an array datatype's size, the number of elements, and the element size are not in agreement it can trigger an out of bounds read. The array datatype stores the full size of the datatype (dt->shared->size) separately from the number of elements (dt->shared->u.array.nelem) and the element size (dt->shared->parent->shared->size). If any one of these are corrupted so that they don't align with the others (element size * nelem = full size), it can lead to an out of bounds read. Depending on what is corrupted, it can alter the type of out of bounds read triggered. The vulnerability is present only in files that have been maliciously altered, as its generally not possible to independently alter the full size of the datatype, the element count and the element size. As such, this is only present if a malicious actor is altering files, and won't appear in regular usage.

AnalysisAI

Out-of-bounds read in HDF5 (all versions prior to 2.0.0) is triggered when parsing a maliciously crafted file whose array datatype metadata violates the internal invariant that element_size × nelem must equal the stored full datatype size. When a victim opens such a file, the HDF5 parser reads beyond its intended buffer boundary, causing application crash or potential memory disclosure. No active exploitation is confirmed in CISA KEV, but SSVC intelligence confirms a POC exists, and the vendor has released a patch in version 2.0.0.

Technical ContextAI

HDF5 (Hierarchical Data Format version 5) is a widely used library and file format for scientific and high-performance computing data storage, maintained by The HDF Group. The vulnerability (CWE-125: Out-of-bounds Read) resides in the array datatype parsing logic. HDF5 array datatypes independently store three interdependent values: the full datatype size (dt->shared->size), the element count (dt->shared->u.array.nelem), and the per-element size (dt->shared->parent->shared->size). The library fails to cross-validate that element_size × nelem equals the declared full size before using these values to guide memory reads. A file where any one of these fields is corrupted relative to the others causes the parser to read out-of-bounds memory. Depending on which field is corrupted, the nature of the resulting OOB read differs. Affected CPE: cpe:2.3:a:hdfgroup:hdf5:*:*:*:*:*:*:*:* covering all HDF Group HDF5 builds below 2.0.0.

RemediationAI

Upgrade HDF5 to version 2.0.0 or later, which contains the vendor-released patch for this out-of-bounds read. The full advisory is published at https://github.com/HDFGroup/hdf5/security/advisories/GHSA-gh44-7wpq-622f. For environments where immediate upgrading is not feasible, restrict HDF5 file ingestion to files sourced exclusively from trusted, integrity-verified origins - for example, by enforcing cryptographic signatures or SHA checksums on all HDF5 files before they reach the parsing layer; this eliminates the attacker's ability to deliver a crafted file without detection. Additionally, sandboxing the HDF5 parsing process using seccomp-bpf profiles, Linux namespaces, or container isolation constrains the blast radius of exploitation to the parsing process only, preventing availability impact from cascading to broader system components. Note that sandboxing does not prevent the OOB read but limits its consequences.