title: Junos OS and Junos OS Evolved: Receipt of a specific LDP message will cause a Denial of Service
description: In an MPLS P2MP environment a Loop with Unreachable Exit Condition vulnerability in the routing protocol daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause high load on RPD which in turn may lead to routing protocol flaps. If a system with sensor-based-stats enabled receives a specific LDP FEC this can lead to the above condition. Continued receipted of such an LDP FEC will create a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS 19.2 version 19.2R2 and later versions prior to 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S2; 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S2, 20.3R2. This issue does not affect Juniper Networks Junos OS versions prior to 19.2R2. Juniper Networks Junos OS Evolved All versions prior to 20.1R2-S3-EVO; 20.3 versions prior to 20.3R1-S2-EVO.
problem types: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
affected:
{
product: Junos OS
vendor: Juniper Networks
versions:
lessThan: 19.2R2, status: unaffected, version: unspecified, versionType: custom
changes: [at: 19.2R3-S3, status: unaffected], lessThan: 19.2*, status: affected, version: 19.2R2, versionType: custom
lessThan: 19.3R2-S6, 19.3R3-S2, status: affected, version: 19.3, versionType: custom
lessThan: 19.4R1-S4, 19.4R2-S4, 19.4R3-S2, status: affected, version: 19.4, versionType: custom
lessThan: 20.1R2-S1, 20.1R3, status: affected, version: 20.1, versionType: custom
lessThan: 20.2R2-S1, 20.2R3, status: affected, version: 20.2, versionType: custom
lessThan: 20.3R1-S2, 20.3R2, status: affected, version: 20.3, versionType: custom
}
{
product: Junos OS Evolved
vendor: Juniper Networks
versions:
lessThan: 20.1R2-S3-EVO, status: affected, version: unspecified, versionType: custom
lessThan: 20.3R1-S2-EVO, status: affected, version: 20.3, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: ADJACENT_NETWORK
availabilityImpact: HIGH
baseScore: 6.5
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 in Junos OS: 19.2R3-S3, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S2, 20.1R2-S1, 20.1R3, 20.2R2-S1, 20.2R3, 20.3R1-S2, 20.3R2, 20.4R1, and all subsequent releases.
The following software releases have been updated to resolve this specific issue in Junos OS Evolved: 20.1R2-S3-EVO, 20.3R1-S2-EVO, 20.4R1-EVO, and all subsequent releases.
workarounds: For Junos OS turn off sensor-based-stats by deleting:
[protocols ldp traffic-statistics sensor-based-stats]
For Junos OS Evolved mLDP will have to be turned off as sensor-based-stats is the default:
[protocols ldp p2mp]