title: Junos OS: Denial of service vulnerability in telnetd
description: A denial of service vulnerability in telnetd service on Juniper Networks Junos OS allows remote unauthenticated attackers to cause a denial of service. Affected Junos OS releases are: 12.1X46 prior to 12.1X46-D71; 12.3X48 prior to 12.3X48-D50; 14.1 prior to 14.1R8-S5, 14.1R9; 14.1X53 prior to 14.1X53-D50; 14.2 prior to 14.2R7-S9, 14.2R8; 15.1 prior to 15.1F2-S16, 15.1F5-S7, 15.1F6-S6, 15.1R5-S2, 15.1R6; 15.1X49 prior to 15.1X49-D90; 15.1X53 prior to 15.1X53-D47; 16.1 prior to 16.1R4-S1, 16.1R5; 16.2 prior to 16.2R1-S3, 16.2R2;
problem types: denial of service
affected:
{
product: Junos OS
vendor: Juniper Networks
versions:
status: affected, version: 12.1X46 prior to 12.1X46-D71
status: affected, version: 12.3X48 prior to 12.3X48-D50
status: affected, version: 14.1 prior to 14.1R8-S5, 14.1R9
status: affected, version: 14.1X53 prior to 14.1X53-D50
status: affected, version: 14.2 prior to 14.2R7-S9, 14.2R8
status: affected, version: 15.1 prior to 15.1F2-S16, 15.1F5-S7, 15.1F6-S6, 15.1R5-S2, 15.1R6
status: affected, version: 15.1X49 prior to 15.1X49-D90
status: affected, version: 15.1X53 prior to 15.1X53-D47
status: affected, version: 16.1 prior to 16.1R4-S1, 16.1R5
status: affected, version: 16.2 prior to 16.2R1-S3, 16.2R2
}
metrics:
cvssV3_0: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: LOW
baseScore: 5.3
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
version: 3.0
]
workarounds: Disabling the telnet service would completely mitigate this issue.
Reducing the maximum number of connections to a value between 1 and 250 would help mitigate this vulnerability.
For example:
user@junos# set system services telnet connection-limit 100