SSH Host Keys < 2048 Bits Considered Weak

low Nessus Plugin ID 153954
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.


The SSH server running on the remote host has public key that is considered weak.


The remote SSH server has a host key size that is smaller than 2048 bits. NIST Special Publication 800-57 Part 3 Recommendation for Key Management recommends RSA keys greater or equal to 2048 bits in length.


Generate a new, larger SSH host key.

See Also

Plugin Details

Severity: Low

ID: 153954

File Name: ssh_key_size_weak.nasl

Version: 1.2

Type: remote

Family: General

Published: 10/13/2021

Updated: 10/13/2021

Dependencies: ssh_detect.nasl

Risk Information

CVSS Score Source: manual

CVSS Score Rationale: Tenable score for weak host key


Risk Factor: Low

Base Score: 2.6

Vector: AV:N/AC:H/Au:N/C:P/I:N/A:N


Risk Factor: Low

Base Score: 3.7

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Vulnerability Information

Excluded KB Items: global_settings/supplied_logins_only