CVE-2026-31970

HIGHNVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 63% 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, nvd
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.1Exploit: None knownExposed: 0

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

HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, bgzf_index_load_hfile(), it was possible to trigger an integer overflow, leading to an under- or zero-sized buffer being allocated to store the index. Sixteen zero bytes would then be written to this buffer, and, depending on the result of the overflow the rest of the file may also be loaded into the buffer as well. If the function did attempt to load the data, it would eventually fail due to not reading the expected number of records, and then try to free the overflowed heap buffer. Exploiting this bug causes a heap buffer overflow. If a user opens a file crafted to exploit this issue, it could lead to the program crashing, or overwriting of data and heap structures in ways not expected by the program. It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. The easiest work-around is to discard any .gzi index files from untrusted sources, and use the bgzip -r option to recreate them.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: 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
Severity81% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
39%
KEV
Not listed

Published

March 18, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
Patch available. Sources: github_commit, github.
generic

oss-security - CVE-2026-31970: HTSlib <= 1.23 heap buffer overflow in the BGZF index file reader

http://www.openwall.com/lists/oss-security/2026/03/18/9
github Patch Available

Heap buffer overflow in HTSlib BGZF index file reader · Advisory · samtools/htslib · GitHub

https://github.com/samtools/htslib/security/advisories/GHSA-p345-84hx-fq6q
github_commit Patch Available

commit 6dd0d7d0e9e7 (samtools/htslib)

Patch available: samtools/htslib 1.23.1 (contains commit 6dd0d7d0e9e7)

https://github.com/samtools/htslib/commit/6dd0d7d0e9e7e2e173a28969e624db8bc8bb5828

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
htslib1.11-4 ... 1.22.1+ds2-1 (23 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
htslib1.16+ds-3 ... 1.22.1+ds2-1 (17 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
htslib1.21+ds-1, 1.22.1+ds-1, 1.22.1+ds-2, 1.22.1+ds2-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
htslib1.21+ds-1, 1.22.1+ds-1, 1.22.1+ds-2, 1.22.1+ds2-1——

Weakness Classification(5)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 30× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 18:08 UTCOSV refresh
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-09-01 04:39 UTCEPSS rescore
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 01:22 UTCEPSS rescore
  22. 2026-08-28 21:41 UTCEPSS rescore
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:49 UTCEPSS rescore
Show 39 more
  1. 2026-08-24 14:17 UTCEPSS rescore
  2. 2026-08-23 00:19 UTCEPSS rescore
  3. 2026-08-21 23:49 UTCEPSS rescore
  4. 2026-08-20 22:55 UTCEPSS rescore
  5. 2026-08-20 22:55 UTCEPSS rescore
  6. 2026-08-19 17:03 UTCEPSS rescore
  7. 2026-08-18 13:48 UTCEPSS rescore
  8. 2026-08-17 13:47 UTCEPSS rescore
  9. 2026-08-16 14:56 UTCEPSS rescore
  10. 2026-08-16 11:14 UTCEG score recompute
  11. 2026-08-16 02:14 UTCEPSS rescore
  12. 2026-08-15 01:30 UTCEPSS rescore
  13. 2026-08-14 07:23 UTCEG score recompute
  14. 2026-08-13 22:00 UTCEPSS rescore
  15. 2026-08-12 22:09 UTCEG score recompute
  16. 2026-08-12 13:50 UTCEPSS rescore
  17. 2026-08-11 21:30 UTCEG score recompute
  18. 2026-08-11 04:35 UTCEG score recompute
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-09 19:00 UTCEG score recompute
  21. 2026-08-09 13:46 UTCEPSS rescore
  22. 2026-08-09 06:57 UTCEG score recompute
  23. 2026-08-08 16:37 UTCEPSS rescore
  24. 2026-08-07 17:30 UTCEG score recompute
  25. 2026-08-06 19:28 UTCEG score recompute
  26. 2026-08-06 13:46 UTCEPSS rescore
  27. 2026-08-06 01:37 UTCEG score recompute
  28. 2026-08-05 19:17 UTCEPSS rescore
  29. 2026-08-04 15:10 UTCEPSS rescore
  30. 2026-08-04 10:38 UTCEPSS rescore
  31. 2026-08-04 00:47 UTCEG score recompute
  32. 2026-08-03 10:36 UTCEPSS rescore
  33. 2026-08-02 16:39 UTCEG score recompute
  34. 2026-08-01 04:16 UTCEPSS rescore
  35. 2026-07-30 16:28 UTCEPSS rescore
  36. 2026-07-30 01:30 UTCEPSS rescore
  37. 2026-07-28 15:36 UTCEPSS rescore
  38. 2026-07-27 14:41 UTCEG score recompute
  39. 2026-07-27 14:27 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-31970?
CVE-2026-31970 is a high vulnerability published on March 18, 2026. HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, bgzfindexload_hfile(), it was possible to trigger an integer overflow, leading to an under- or zero-sized buffer being allocated to…
When was CVE-2026-31970 disclosed?
CVE-2026-31970 was first published in the National Vulnerability Database on March 18, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-31970 actively exploited?
CVE-2026-31970 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 61.5% of all scored CVEs.
What is the CVSS score of CVE-2026-31970?
CVE-2026-31970 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-31970?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-31970, 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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