CVE-2026-26199

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 80% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this weekElevated
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 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.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
20%
KEV
Not listed

Published

July 20, 2026

Last Modified

July 23, 2026

Advisory Details (2)

Auto-updated Jul 20, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Buffer underflow in `H5Iget_name `/`H5G_get_name` if size is zero · Advisory · HDFGroup/hdf5 · GitHub

https://github.com/HDFGroup/hdf5/security/advisories/GHSA-5c6x-jmgf-f5vc
generic

hdf5/src/H5Gname.c at develop · HDFGroup/hdf5 · GitHub

https://github.com/HDFGroup/hdf5/blob/develop/src/H5Gname.c#L474

Vendor Advisories for CVE-2026-26199(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 18× in last 7d / 18× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-27 06:47 UTCEG score recompute
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-26 14:54 UTCEPSS rescore
  4. 2026-07-26 04:30 UTCEG score recompute
  5. 2026-07-25 14:18 UTCEPSS rescore
  6. 2026-07-25 14:17 UTCEPSS rescore
  7. 2026-07-24 14:17 UTCEPSS rescore
  8. 2026-07-23 14:18 UTCEPSS rescore
  9. 2026-07-23 14:18 UTCEPSS rescore
  10. 2026-07-23 03:07 UTCEG score recompute
  11. 2026-07-22 14:08 UTCEPSS rescore
  12. 2026-07-22 14:08 UTCEPSS rescore
  13. 2026-07-21 15:24 UTCEPSS rescore
  14. 2026-07-21 15:24 UTCEPSS rescore
  15. 2026-07-20 19:39 UTCEG score recompute
  16. 2026-07-20 16:37 UTCEG score recompute
  17. 2026-07-20 15:23 UTCEG score recompute
  18. 2026-07-20 15:22 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-26199?
CVE-2026-26199 is a medium vulnerability published on July 20, 2026. HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If H5Igetname is invoked on a group id with 0 for the size parameter, it will underflow when trying to place a null terminator in the buffer. This can occur if H5Igetname is invoked in a way…
When was CVE-2026-26199 disclosed?
CVE-2026-26199 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26199 actively exploited?
CVE-2026-26199 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 79.6% of all scored CVEs.
What is the CVSS score of CVE-2026-26199?
CVE-2026-26199 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-26199?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-26199, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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