CVE-2026-59843

MEDIUMPre-NVD 6.56.5
EchelonGraph scoreMEDIUM confidence

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

Score 6.5 from GitHub Security Advisory published 2026-07-21. A secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-46177 (ENISA EUVD) · GHSA-4846-7xwg-pw5m (GitHub Security Advisories)Source: ENISA EUVD

6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 6.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
30
EG Risk 30/100

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)
Severity65% × 45%
Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 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 every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.7%
EPSS %ILE
53rd
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 (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.

EG Severity
6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.7% 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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.

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

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 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 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

July 21, 2026

Last Modified

September 1, 2026

Advisory Details (2)

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

2498176 – (CVE-2026-59843) CVE-2026-59843 libssh: libssh: denial of service via zero advertised channel packet size

https://bugzilla.redhat.com/show_bug.cgi?id=2498176
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-59843

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibssh-gcrypt-dev (0.9.6-2ubuntu0.22.04.8) @ jammy2026-10-22ubuntu
redhatlibssh-0:0.9.6-17.el8_102026-09-01redhat
redhatlibssh-0:0.10.4-19.el9_82026-09-01redhat
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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
libssh0.10.4-1 ... 0.9.8-0+deb11u2 (25 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libssh0.10.5-2 ... 0.12.2-1 (17 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libssh0.11.2-1, 0.11.2-1+deb13u1, 0.11.3-1
  • every version up to 0.11.5-0+deb13u1: fixed in 0.11.5-0+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libssh0.11.2-1 ... 0.12.1-1 (6 versions)
  • every version up to 0.12.2-1: fixed in 0.12.2-1
—

Weakness Classification(2)

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

Additional Vendor Advisories

(2)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 46× 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 280 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 180 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 0.7% · 53rd percentile
  2. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  3. 2026-10-25 14:16 UTCEG score recompute
  4. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  5. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  6. 2026-10-22 20:56 UTCEG score recompute
  7. 2026-10-22 20:56 UTCVendor advisory
  8. 2026-10-22 20:56 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  9. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  10. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  11. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  12. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  13. 2026-10-18 03:27 UTCEG score recompute
  14. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  15. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  16. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  17. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  18. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  20. 2026-10-12 15:52 UTCEG score recompute
  21. 2026-10-11 19:36 UTCEG score recompute
  22. 2026-10-11 16:51 UTCEG score recompute
  23. 2026-10-11 14:13 UTCEG score recompute
  24. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
Show 75 more
  1. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  2. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  3. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  5. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  7. 2026-10-04 14:52 UTCEG score recompute
  8. 2026-10-04 14:52 UTCVendor advisory
  9. 2026-10-04 14:52 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  10. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  11. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  12. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-10-01 07:36 UTCEG score recompute
  14. 2026-10-01 07:36 UTCVendor advisory
  15. 2026-10-01 07:36 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  16. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  18. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-09-28 06:13 UTCEG score recompute
  20. 2026-09-28 06:13 UTCVendor advisory
  21. 2026-09-28 06:13 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  22. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  23. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  24. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-09-24 03:25 UTCEG score recompute
  26. 2026-09-24 03:25 UTCVendor advisory
  27. 2026-09-24 03:25 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  28. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  29. 2026-09-23 01:32 UTCEG score recompute
  30. 2026-09-23 01:32 UTCVendor advisory
  31. 2026-09-23 01:32 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  32. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  33. 2026-09-20 06:07 UTCEG score recompute
  34. 2026-09-20 06:07 UTCVendor advisory
  35. 2026-09-20 06:07 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  36. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  37. 2026-09-18 03:52 UTCEG score recompute
  38. 2026-09-18 03:52 UTCVendor advisory
  39. 2026-09-18 03:52 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  40. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  41. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  42. 2026-09-16 12:42 UTCEG score recompute
  43. 2026-09-16 12:42 UTCVendor advisory
  44. 2026-09-16 12:42 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  45. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  46. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  47. 2026-09-14 08:04 UTCEG score recompute
  48. 2026-09-14 08:04 UTCVendor advisory
  49. 2026-09-14 08:04 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  50. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  51. 2026-09-13 08:57 UTCEG score recompute
  52. 2026-09-13 08:57 UTCVendor advisory
  53. 2026-09-13 08:57 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  54. 2026-09-12 09:50 UTCEG score recompute
  55. 2026-09-12 09:50 UTCVendor advisory
  56. 2026-09-12 09:50 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  57. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  58. 2026-09-11 09:13 UTCEG score recompute
  59. 2026-09-11 09:13 UTCVendor advisory
  60. 2026-09-11 09:13 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  61. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  62. 2026-09-09 11:40 UTCEG score recompute
  63. 2026-09-09 11:40 UTCVendor advisory
  64. 2026-09-09 11:40 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  65. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  66. 2026-09-07 22:44 UTCEG score recompute
  67. 2026-09-07 22:44 UTCVendor advisory
  68. 2026-09-07 22:44 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  69. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  70. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 44th percentile
  71. 2026-09-06 11:19 UTCEG score recompute
  72. 2026-09-06 11:19 UTCVendor advisory
  73. 2026-09-06 11:19 UTCGHSA enrichmentGHSA-4846-7xwg-pw5m · GitHub CVSS 6.5
  74. 2026-09-05 09:13 UTCEG score recompute
  75. 2026-09-05 09:13 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-59843?
CVE-2026-59843 is a medium-severity vulnerability; its CVE record was published on July 21, 2026. A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSHMSGCHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.
When was CVE-2026-59843 made public?
CVE-2026-59843 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 September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-59843 actively exploited?
CVE-2026-59843 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (53rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59843?
CVE-2026-59843 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-59843?
A fix for CVE-2026-59843 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59843 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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