CVE-2026-59851

HIGHPre-NVD 8.88.8
EchelonGraph scoreMEDIUM confidence

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

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-21. A secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-46268 (ENISA EUVD) · GHSA-x5cr-v39m-53gw (GitHub Security Advisories)Source: ENISA EUVD

8.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
40
EG Risk 40/100

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)
Severity88% × 45%
Impact severity (EG Severity): CVSS 8.8 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.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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.
EPSS PROB
0.5%
EPSS %ILE
41st
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 (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.

EG Severity
8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

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

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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

July 21, 2026

Last Modified

August 17, 2026

Advisory Details (2)

Auto-updated Jul 21, 2026
Patch available. Sources: redhat.
Red Hat

2498184 – (CVE-2026-59851) CVE-2026-59851 libssh: libssh: authentication bypass via missing GSSAPI principal check

https://bugzilla.redhat.com/show_bug.cgi?id=2498184
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-59851

Vendor Advisories for CVE-2026-59851(3)

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

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatlibssh-0:0.12.0-3.el10_22026-08-17redhat
redhatlibssh-main-0.12.1-4.hum12026-07-21redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libssh0.11.2-1, 0.11.3-1, 0.12.0-1, 0.12.0-2, 0.12.0-3
  • every version up to 0.12.1-1: fixed in 0.12.1-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 50× 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 100 of 343 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. None are among the latest 100 rows. The 243 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  3. 2026-10-25 14:16 UTCEG score recompute
  4. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  7. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  9. 2026-10-20 09:38 UTCEG score recompute
  10. 2026-10-20 09:38 UTCVendor advisory
  11. 2026-10-20 09:37 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  12. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  13. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  14. 2026-10-18 03:27 UTCEG score recompute
  15. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  16. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  18. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  19. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  20. 2026-10-13 15:49 UTCEG score recompute
  21. 2026-10-13 15:49 UTCVendor advisory
  22. 2026-10-13 15:48 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  24. 2026-10-12 15:52 UTCEG score recompute
  25. 2026-10-11 19:36 UTCEG score recompute
Show 75 more
  1. 2026-10-11 16:51 UTCEG score recompute
  2. 2026-10-11 14:13 UTCEG score recompute
  3. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  6. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  7. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  8. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  9. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  10. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  11. 2026-10-04 14:50 UTCEG score recompute
  12. 2026-10-04 14:50 UTCVendor advisory
  13. 2026-10-04 14:50 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  14. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  15. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  16. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  17. 2026-10-01 07:30 UTCEG score recompute
  18. 2026-10-01 07:30 UTCVendor advisory
  19. 2026-10-01 07:30 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  20. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  21. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  22. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  23. 2026-09-28 06:10 UTCEG score recompute
  24. 2026-09-28 06:10 UTCVendor advisory
  25. 2026-09-28 06:10 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  26. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  27. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  28. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  29. 2026-09-24 03:24 UTCEG score recompute
  30. 2026-09-24 03:24 UTCVendor advisory
  31. 2026-09-24 03:24 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  32. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  33. 2026-09-23 01:26 UTCEG score recompute
  34. 2026-09-23 01:26 UTCVendor advisory
  35. 2026-09-23 01:26 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  36. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  37. 2026-09-20 05:58 UTCEG score recompute
  38. 2026-09-20 05:58 UTCVendor advisory
  39. 2026-09-20 05:58 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  40. 2026-09-19 00:23 UTCEG score recompute
  41. 2026-09-19 00:23 UTCVendor advisory
  42. 2026-09-19 00:23 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  43. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  44. 2026-09-18 03:50 UTCEG score recompute
  45. 2026-09-18 03:50 UTCVendor advisory
  46. 2026-09-18 03:50 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  47. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  48. 2026-09-17 05:06 UTCEG score recompute
  49. 2026-09-17 05:06 UTCVendor advisory
  50. 2026-09-17 05:06 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  51. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  52. 2026-09-16 12:39 UTCEG score recompute
  53. 2026-09-16 12:39 UTCVendor advisory
  54. 2026-09-16 12:39 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  55. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  56. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  57. 2026-09-14 04:25 UTCEG score recompute
  58. 2026-09-14 04:25 UTCVendor advisory
  59. 2026-09-14 04:25 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  60. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  61. 2026-09-13 15:57 UTCVendor advisory
  62. 2026-09-13 15:57 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  63. 2026-09-13 02:59 UTCEG score recompute
  64. 2026-09-13 02:59 UTCVendor advisory
  65. 2026-09-13 02:59 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  66. 2026-09-12 10:03 UTCVendor advisory
  67. 2026-09-12 10:03 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  68. 2026-09-11 21:34 UTCEG score recompute
  69. 2026-09-11 21:34 UTCVendor advisory
  70. 2026-09-11 21:34 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  71. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 21st percentile
  72. 2026-09-11 09:06 UTCEG score recompute
  73. 2026-09-11 09:06 UTCVendor advisory
  74. 2026-09-11 09:06 UTCGHSA enrichmentGHSA-x5cr-v39m-53gw · GitHub severity HIGH · GitHub CVSS 8.8
  75. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 21st percentile

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Frequently asked(5)

What is CVE-2026-59851?
CVE-2026-59851 is a high-severity vulnerability; its CVE record was published on July 21, 2026. A flaw was found in libssh. On servers with GSSAPIKeyExchange enabled, the gssapi-keyex path does not verify whether the authenticated Kerberos principal is authorized for the requested local user, allowing authenticated clients to log in as arbitrary users.
When was CVE-2026-59851 made public?
CVE-2026-59851 was made public on July 21, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on July 21, 2026. EchelonGraph's copy of the record carries a last-modified date of August 17, 2026; the record at its source may have been updated since.
Is CVE-2026-59851 actively exploited?
CVE-2026-59851 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59851?
CVE-2026-59851 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-59851?
A fix for CVE-2026-59851 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59851 are linked in the Vendor Advisories panel on this page.

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