CVE-2026-31966

CRITICALNVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.5% (45th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-12936 (ENISA EUVD)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. As one method of removing redundant data, CRAM uses reference-based compression so that instead of storing the full sequence for each alignment record it stores a location in an external reference sequence along with a list of differences to the reference at that location as a sequence of "features". When decoding CRAM records, the reference data is stored in a char array, and parts matching the alignment record sequence are copied over as necessary. Due to insufficient validation of the feature data series, it was possible to make the cram_decode_seq() function copy data from either before the start, or after the end of the stored reference either into the buffer used to store the output sequence for the cram record, or into the buffer used to build the SAM MD tag. This allowed arbitrary data to be leaked to the calling function. This bug may allow information about program state to be leaked. It may also cause a program crash through an attempt to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
56
EG Risk 56/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
45th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 18, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Sep 16, 2026
Patch available. Sources: github_commit, github.
GitHub advisoryMentions a patch (unverified)

Out-of-bounds read in HTSlib CRAM reader due to improper validation of input · Advisory · samtools/htslib · GitHub

https://github.com/samtools/htslib/security/advisories/GHSA-5cj8-mj52-8vp3
GitHub commit Patch Available

commit 4a5ef25eb1fb (samtools/htslib)

Patch available: samtools/htslib 1.23.1 (contains commit 4a5ef25eb1fb)

https://github.com/samtools/htslib/commit/4a5ef25eb1fb3d64438103316fffe423b2c3f5f4
GitHub commit Patch Available

commit 2a45eb129d70 (samtools/htslib)

Patch available: samtools/htslib 1.23.1 (contains commit 2a45eb129d70)

https://github.com/samtools/htslib/commit/2a45eb129d703ad27f9fabc8169f0e94d3c69fa3
GitHub commit Patch Available

commit 22ec5230ef95 (samtools/htslib)

Patch available: samtools/htslib 1.23.1 (contains commit 22ec5230ef95)

https://github.com/samtools/htslib/commit/22ec5230ef95769ab009420da69568c7e530af28

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
htslib1.11-4 ... 1.22.1+ds2-1 (23 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
htslib1.16+ds-3 ... 1.24-3 (20 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
htslib1.21+ds-1 ... 1.24-3 (7 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
htslib1.21+ds-1 ... 1.24-3 (7 versions)
  • every version on: no fix on record
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 55× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 95 of 123 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 5 repeat rows among the latest 100 are merged into the row they repeat. The 28 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 21:44 UTCEG score recompute
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  3. 2026-10-31 19:19 UTCEG score recompute
  4. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  5. 2026-10-30 16:55 UTCEG score recompute
  6. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  7. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  8. 2026-10-29 14:31 UTCEG score recompute
  9. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  10. 2026-10-28 12:06 UTCEG score recompute
  11. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  12. 2026-10-27 09:41 UTCEG score recompute
  13. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  14. 2026-10-26 07:17 UTCEG score recompute
  15. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  16. 2026-10-25 14:36 UTCEG score recompute
  17. 2026-10-25 04:53 UTCEG score recompute
  18. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  19. 2026-10-24 02:29 UTCEG score recompute
  20. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  21. 2026-10-23 00:04 UTCEG score recompute
  22. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  23. 2026-10-21 21:37 UTCEG score recompute
  24. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  25. 2026-10-20 18:50 UTCEG score recompute
Show 70 more
  1. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  2. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  3. 2026-10-19 16:22 UTCEG score recompute
  4. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  5. 2026-10-18 03:48 UTCEG score recompute
  6. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  7. 2026-10-17 11:32 UTCEG score recompute
  8. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  9. 2026-10-16 09:07 UTCEG score recompute
  10. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  11. 2026-10-15 06:42 UTCEG score recompute
  12. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  13. 2026-10-14 02:24 UTCEG score recompute
  14. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  15. 2026-10-12 22:38 UTCEG score recompute
  16. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  17. 2026-10-12 16:14 UTCEG score recompute
  18. 2026-10-11 19:57 UTCEG score recompute
  19. 2026-10-11 17:10 UTCEG score recompute
  20. 2026-10-11 14:38 UTCEG score recompute
  21. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  22. 2026-10-11 09:14 UTCOSV refresh
  23. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  24. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  25. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  26. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  27. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  28. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  29. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  30. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  31. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  32. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  33. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  34. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  35. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  36. 2026-09-21 21:45 UTCOSV refresh
  37. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  38. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  39. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  40. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  41. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  42. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  43. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  44. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  45. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  46. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  47. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  48. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  49. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  50. 2026-09-02 18:08 UTCOSV refresh
  51. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  52. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  53. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  54. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  55. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  56. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  57. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  58. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  59. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  60. 2026-08-24 14:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  61. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  62. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  63. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  64. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  65. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  66. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  67. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  68. 2026-08-16 11:14 UTCEG score recompute
  69. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  70. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-31966?
CVE-2026-31966 is a critical-severity vulnerability; its CVE record was published on March 18, 2026. HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. As one method of removing redundant data, CRAM uses reference-based compression so that instead of storing the full sequence for each alignment record it…
When was the CVE record for CVE-2026-31966 published?
The CVE record for CVE-2026-31966 was published on March 18, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-31966 actively exploited?
CVE-2026-31966 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (45th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-31966?
CVE-2026-31966 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-31966?
A fix for CVE-2026-31966 is available: update to the fixed version the vendor names in its advisory.

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