Cyber Resilience

CVE-2026-26199

Memory Safety in Hdfgroup Hdf5 ≤ 2.1.0

Public PoCMemory Safety
Published
20 July 2026
Modified
29 July 2026
Patch / advisory
View advisory
CVSS Score v4 5.9
Click a component to see what it means
Raw vectorCVSS: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 Score 0.0026 17th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-26199 is a medium-severity Buffer Underflow (CWE-124) vulnerability in Hdfgroup Hdf5. Its CVSS base score is 5.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 17th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If `H5Iget_name` is invoked on a group id with `0` for the size parameter, it will underflow when trying to place a null terminator…

more

in the buffer. This can occur if `H5Iget_name` is invoked in a way where `size` can be forced to zero, and there is important data before the `name` buffer.

CWE(s)
CWE-124

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-29164Same product: Hdfgroup Hdf5
CVE-2026-34734Same product: Hdfgroup Hdf5
CVE-2024-33876Same product: Hdfgroup Hdf5
CVE-2024-29160Same product: Hdfgroup Hdf5
CVE-2026-29043Same product: Hdfgroup Hdf5
CVE-2024-32616Same product: Hdfgroup Hdf5
CVE-2024-29162Same product: Hdfgroup Hdf5
CVE-2024-32617Same product: Hdfgroup Hdf5
CVE-2024-32619Same product: Hdfgroup Hdf5
CVE-2024-29158Same product: Hdfgroup Hdf5

Affected Assets

hdfgroup
hdf5
≤ 2.1.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.4.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and analysis can discover buffer underwrite flaws before deployment but does not stop their introduction.

SI-10 Information Input Validation partial match

Input validation can enforce bounds on indices or pointers before buffer writes, structurally stopping underwrite conditions.

SI-16 Memory Protection partial match

Memory protection mechanisms limit the blast radius of an out-of-bounds write even if the coding flaw exists.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent introduction of buffer underwrite flaws via coding standards, reviews, and testing.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover buffer underwrite issues but do not prevent their creation.

PR.PS-02 partial match
prevents

Patching removes instances of the weakness after discovery but does not address root-cause prevention in code.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches buffer-underflow defects before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates input validation and bounds checking that directly prevent buffer underflow.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify buffer-size and pointer-safety rules.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture and engineering principles require safe memory-handling patterns.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe pointer arithmetic and mandate bounds checks.

References