title: Junos OS Evolved: Telnet service may be enabled when it is expected to be disabled.
description: An Improper Initialization vulnerability in Juniper Networks Junos OS Evolved may cause a commit operation for disabling the telnet service to not take effect as expected, resulting in the telnet service staying enabled. When it is not intended to be operating on the device, an administrator can issue the following command to verify whether telnet is operating in the background: user@device > show system connections | grep :23 tcp 0 0 0.0.0.0:23 0.0.0.0:* LISTEN 20879/xinetd This issue affects: Juniper Networks Junos OS Evolved All versions prior to 20.4R2-S2-EVO; 21.1 version 21.1R1-EVO and later versions; 21.2 versions prior to 21.2R2-EVO.
problem types: CWE-665 Improper Initialization
affected:
{
product: Junos OS Evolved
vendor: Juniper Networks
versions:
lessThan: 20.4R2-S2-EVO, status: affected, version: unspecified, versionType: custom
lessThan: 21.1*, status: affected, version: 21.1R1-EVO, versionType: custom
lessThan: 21.2R2-EVO, status: affected, version: 21.2, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 6.5
baseSeverity: MEDIUM
confidentialityImpact: LOW
integrityImpact: LOW
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
version: 3.1
]
exploits: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
solutions: The following software releases have been updated to resolve this specific issue: Junos OS Evolved: 20.4R2-S2-EVO, 21.2R2-EVO, 21.3R1-EVO and all subsequent releases.
workarounds: To work around the issue, the xinetd service can be restarted manually using one of the commands below:
user@device% systemctl restart xinetd
or
user@device% systemctl restart services-xinetd
Additionally, loopback/firewall filters can be applied to disable remote access to the telnet service.