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Infinite loop with channel maximum_packet_size=0

Moderate
Rob-Hague published GHSA-vhpg-4g9v-rppq Aug 9, 2026

Package

nuget SSH.NET (NuGet)

Affected versions

<=2025.1.0

Patched versions

2026.0.0

Description

Summary

When a server specifies a maximum packet size of 0 upon the opening of a channel, the library enters an infinite loop when it next tries to send data over the channel. The loop which sends slices of the data according to the maximum packet size does not sufficiently account for when the size is 0.

Impact

Post-auth infinite loop DoS

Remediation

The fixed release changes the loop condition such that it exits in the case where the server has sent a maximum packet size of 0.

6ee878f

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVE ID

No known CVE

Weaknesses

Loop with Unreachable Exit Condition ('Infinite Loop')

The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. Learn more on MITRE.

Credits