CVE-2026-59843

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

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, ghsa, secondary
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.5Exploit: None knownExposed: 0

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
6.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

July 21, 2026

Last Modified

September 1, 2026

Advisory Details (2)

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

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
redhat Patch Available

cve-details

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

Vendor Advisories for CVE-2026-59843(5)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibssh-doc (0.11.3-1ubuntu2.1) @ resolute2026-09-11ubuntu
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 rangeFixed inDependents
libssh0.10.4-1 ... 0.9.8-0+deb11u2 (25 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libssh0.10.5-2 ... 0.12.2-1 (17 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libssh0.11.2-1, 0.11.2-1+deb13u1, 0.11.3-10.11.5-0+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libssh0.11.2-1 ... 0.12.1-1 (6 versions)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 20× in last 7d / 110× 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.

Showing the most recent 100 of 199 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-59843?
CVE-2026-59843 is a medium vulnerability 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 disclosed?
CVE-2026-59843 was first published in the National Vulnerability Database on July 21, 2026, with the most recent update on September 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59843 actively exploited?
CVE-2026-59843 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.8% of all scored CVEs.
What is the CVSS score of CVE-2026-59843?
CVE-2026-59843 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-59843?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59843, 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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