CVE-2026-59843

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH 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 — Patch released 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(high)
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
42%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 22, 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(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
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.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 23× in last 7d / 23× 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. 2026-07-27 09:50 UTCEG score recompute
  2. 2026-07-27 09:50 UTCVendor advisory
  3. 2026-07-27 09:50 UTCGHSA enrichment
  4. 2026-07-26 14:54 UTCEPSS rescore
  5. 2026-07-26 14:54 UTCEPSS rescore
  6. 2026-07-26 10:43 UTCEG score recompute
  7. 2026-07-26 10:43 UTCVendor advisory
  8. 2026-07-26 10:43 UTCGHSA enrichment
  9. 2026-07-25 14:18 UTCEPSS rescore
  10. 2026-07-25 14:18 UTCEPSS rescore
  11. 2026-07-24 14:18 UTCEPSS rescore
  12. 2026-07-24 14:18 UTCEPSS rescore
  13. 2026-07-23 14:18 UTCEPSS rescore
  14. 2026-07-23 14:18 UTCEPSS rescore
  15. 2026-07-23 03:21 UTCEG score recompute
  16. 2026-07-22 23:19 UTCEG score recompute
  17. 2026-07-22 23:19 UTCGHSA enrichment
  18. 2026-07-22 14:08 UTCEPSS rescore
  19. 2026-07-22 14:08 UTCEPSS rescore
  20. 2026-07-21 12:58 UTCEG score recompute
  21. 2026-07-21 12:58 UTCGHSA enrichment
  22. 2026-07-21 11:35 UTCEG score recompute
  23. 2026-07-21 11:32 UTCMITRE cvelistV5first tracked

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 July 22, 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 58.0% 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

Explore the affected products and dependency analysis for CVE-2026-59843

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