CVE-2026-59843 - Vulnerability Details - OpenCVE

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.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable no

Technical Impact partial

Vendors	Products
Redhat	Enterprise Linux Hummingbird

No data.

No data.

No data.

References

Link	Providers
https://access.redhat.com/security/cve/CVE-2026-59843
https://bugzilla.redhat.com/show_bug.cgi?id=2498176

History

Tue, 21 Jul 2026 13:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-400
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Tue, 21 Jul 2026 11:45:00 +0000

Type	Values Removed	Values Added
Description		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.
Title		Libssh: libssh: denial of service via zero advertised channel packet size
First Time appeared		Redhat Redhat enterprise Linux Redhat hummingbird
CPEs		cpe:/a:redhat:hummingbird:1 cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9
Vendors & Products		Redhat Redhat enterprise Linux Redhat hummingbird
References		https://access.redhat.com/security/cve/CVE-2026-59843 https://bugzilla.redhat.com/show_bug.cgi?id=2498176
Metrics		cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}`

MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2026-07-21T11:16:12.061Z

Updated: 2026-07-21T12:08:28.113Z

Reserved: 2026-07-07T15:40:24.561Z

Link: CVE-2026-59843

Vulnrichment

Updated: 2026-07-21T12:05:43.803Z

NVD

No data.

Redhat

No data.

OpenCVE Enrichment

No data.

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