CVE-2026-19028

MEDIUMPre-NVD 6.86.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% 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
6.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.8Exploit: Elevated riskExposed: 0

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

H5Z__filter_fletcher32 in H5Zfletcher32.c in HDF5 through 2.3.0 computes the data length to checksum by subtracting the 4-byte trailing checksum size from the input buffer size without checking that the buffer is at least 4 bytes, allowing a size_t underflow. This allows attackers to cause a denial of service (massively out-of-bounds read and application crash in H5_checksum_fletcher32) via a crafted HDF5 file with a Fletcher32-filtered chunk smaller than 4 bytes, triggered via H5Dread, e.g. by the h5ls or h5dump tools.

CVSS v3
6.8
EG Score
6.8(medium)
EG Risk
47(Track)
EG Risk 47/100SSVC: 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
Severity68% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

August 5, 2026

Last Modified

August 6, 2026

Advisory Details (3)

Auto-updated Aug 5, 2026
No patch confirmed yet. Sources: github_pr.
generic

h5ls: SIGSEGV in H5_checksum_fletcher32 due to underflowed checksum length · Issue #6490 · HDFGroup/hdf5 · GitHub

https://github.com/HDFGroup/hdf5/issues/6490
generic

h5dump: SIGSEGV in H5_checksum_fletcher32 due to underflowed checksum length · Issue #6488 · HDFGroup/hdf5 · GitHub

https://github.com/HDFGroup/hdf5/issues/6488
github_pr

Fix h5ls SIGSEGVs in Nbit and Fletcher32 filter decode paths

Upstream fix in progress (PR #6497 · HDFGroup/hdf5, state=open)

https://github.com/HDFGroup/hdf5/pull/6497

Vendor Advisories for CVE-2026-19028(2)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
hdf51.10.10+repack-1 ... 2.1.0+repack-1~exp9 (83 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
hdf51.10.10+repack-1 ... 2.1.0+repack-1~exp9 (72 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
hdf51.14.5+repack-3 ... 2.1.0+repack-1~exp9 (41 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
hdf51.14.5+repack-3 ... 2.1.0+repack-1~exp9 (41 versions)——

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 20× in last 7d / 46× 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. 2026-08-21 04:50 UTCEG score recompute
  2. 2026-08-21 04:50 UTCGHSA enrichment
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-20 03:55 UTCEG score recompute
  5. 2026-08-20 03:55 UTCGHSA enrichment
  6. 2026-08-19 17:03 UTCEPSS rescore
  7. 2026-08-19 03:00 UTCEG score recompute
  8. 2026-08-19 03:00 UTCGHSA enrichment
  9. 2026-08-18 13:48 UTCEPSS rescore
  10. 2026-08-18 01:44 UTCEG score recompute
  11. 2026-08-18 01:44 UTCGHSA enrichment
  12. 2026-08-17 13:47 UTCEPSS rescore
  13. 2026-08-17 00:49 UTCEG score recompute
  14. 2026-08-17 00:49 UTCGHSA enrichment
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-16 02:14 UTCEPSS rescore
  17. 2026-08-15 23:54 UTCEG score recompute
  18. 2026-08-15 23:54 UTCGHSA enrichment
  19. 2026-08-15 01:30 UTCEPSS rescore
  20. 2026-08-14 22:59 UTCGHSA enrichment
  21. 2026-08-13 22:04 UTCEG score recompute
  22. 2026-08-13 22:04 UTCGHSA enrichment
  23. 2026-08-13 22:00 UTCEPSS rescore
  24. 2026-08-12 21:10 UTCEG score recompute
  25. 2026-08-12 21:10 UTCGHSA enrichment
Show 21 more
  1. 2026-08-12 13:50 UTCEPSS rescore
  2. 2026-08-11 20:05 UTCEG score recompute
  3. 2026-08-11 20:05 UTCGHSA enrichment
  4. 2026-08-11 13:42 UTCEPSS rescore
  5. 2026-08-11 00:00 UTCEPSS rescore
  6. 2026-08-10 19:09 UTCGHSA enrichment
  7. 2026-08-09 18:13 UTCEG score recompute
  8. 2026-08-09 18:13 UTCGHSA enrichment
  9. 2026-08-09 13:46 UTCEPSS rescore
  10. 2026-08-08 17:19 UTCEG score recompute
  11. 2026-08-08 17:19 UTCGHSA enrichment
  12. 2026-08-08 16:37 UTCEPSS rescore
  13. 2026-08-07 16:23 UTCGHSA enrichment
  14. 2026-08-06 15:29 UTCEG score recompute
  15. 2026-08-06 15:29 UTCGHSA enrichment
  16. 2026-08-06 14:45 UTCEG score recompute
  17. 2026-08-06 14:45 UTCGHSA enrichment
  18. 2026-08-06 13:46 UTCEPSS rescore
  19. 2026-08-06 00:19 UTCEG score recompute
  20. 2026-08-05 23:20 UTCEG score recompute
  21. 2026-08-05 23:20 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-19028?
CVE-2026-19028 is a medium vulnerability published on August 5, 2026. H5Zfilterfletcher32 in H5Zfletcher32.c in HDF5 through 2.3.0 computes the data length to checksum by subtracting the 4-byte trailing checksum size from the input buffer size without checking that the buffer is at least 4 bytes, allowing a sizet underflow. This allows attackers to cause a denial of…
When was CVE-2026-19028 disclosed?
CVE-2026-19028 was first published in the National Vulnerability Database on August 5, 2026, with the most recent update on August 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-19028 actively exploited?
CVE-2026-19028 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 97.2% of all scored CVEs.
What is the CVSS score of CVE-2026-19028?
CVE-2026-19028 has a CVSS v3 base score of 6.8 (NVD).
How do I remediate CVE-2026-19028?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-19028, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-19028

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