CVE-2026-19027

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.9 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
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: Elevated riskExposed: 0

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

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.

CVSS v3
6.9
EG Score
6.9(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
Severity69% × 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

Issue · GitHub

https://github.com/HDFGroup/hdf5/issues/6492
generic

h5ls: SIGSEGV in Nbit filter processing when dumping datasets · Issue #6489 · HDFGroup/hdf5 · GitHub

https://github.com/HDFGroup/hdf5/issues/6489
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-2026-19027(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(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 45× 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. 2026-08-20 12:28 UTCEG score recompute
  2. 2026-08-20 12:28 UTCGHSA enrichment
  3. 2026-08-19 17:03 UTCEPSS rescore
  4. 2026-08-19 10:51 UTCEG score recompute
  5. 2026-08-19 10:51 UTCGHSA enrichment
  6. 2026-08-18 13:48 UTCEPSS rescore
  7. 2026-08-18 09:14 UTCEG score recompute
  8. 2026-08-18 09:14 UTCGHSA enrichment
  9. 2026-08-17 13:47 UTCEPSS rescore
  10. 2026-08-17 07:37 UTCEG score recompute
  11. 2026-08-17 07:37 UTCGHSA enrichment
  12. 2026-08-16 14:56 UTCEPSS rescore
  13. 2026-08-16 06:00 UTCEG score recompute
  14. 2026-08-16 06:00 UTCGHSA enrichment
  15. 2026-08-16 02:14 UTCEPSS rescore
  16. 2026-08-15 04:24 UTCEG score recompute
  17. 2026-08-15 04:24 UTCGHSA enrichment
  18. 2026-08-15 01:30 UTCEPSS rescore
  19. 2026-08-14 02:47 UTCEG score recompute
  20. 2026-08-14 02:46 UTCGHSA enrichment
  21. 2026-08-13 22:00 UTCEPSS rescore
  22. 2026-08-13 01:09 UTCEG score recompute
  23. 2026-08-13 01:09 UTCGHSA enrichment
  24. 2026-08-12 13:50 UTCEPSS rescore
  25. 2026-08-11 23:32 UTCEG score recompute
Show 20 more
  1. 2026-08-11 23:32 UTCGHSA enrichment
  2. 2026-08-11 13:42 UTCEPSS rescore
  3. 2026-08-11 00:00 UTCEPSS rescore
  4. 2026-08-10 21:56 UTCGHSA enrichment
  5. 2026-08-09 20:19 UTCEG score recompute
  6. 2026-08-09 20:19 UTCGHSA enrichment
  7. 2026-08-09 13:46 UTCEPSS rescore
  8. 2026-08-08 18:43 UTCEG score recompute
  9. 2026-08-08 18:43 UTCGHSA enrichment
  10. 2026-08-08 16:37 UTCEPSS rescore
  11. 2026-08-07 17:06 UTCEG score recompute
  12. 2026-08-07 17:06 UTCGHSA enrichment
  13. 2026-08-06 15:29 UTCEG score recompute
  14. 2026-08-06 15:29 UTCGHSA enrichment
  15. 2026-08-06 14:45 UTCEG score recompute
  16. 2026-08-06 14:45 UTCGHSA enrichment
  17. 2026-08-06 13:46 UTCEPSS rescore
  18. 2026-08-06 00:19 UTCEG score recompute
  19. 2026-08-05 23:20 UTCEG score recompute
  20. 2026-08-05 23:20 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-19027?
CVE-2026-19027 is a medium vulnerability published on August 5, 2026. The H5Znbitdecompressonebyte, H5Znbitdecompressonenooptype, and H5Znbitdecompressone_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…
When was CVE-2026-19027 disclosed?
CVE-2026-19027 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-2026-19027 actively exploited?
CVE-2026-19027 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-2026-19027?
CVE-2026-19027 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-19027?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-19027, 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-2026-19027

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