title: Junos OS and Junos OS Evolved: RPD could crash in SR-ISIS/MPLS environment due to a flap of an ISIS link in the network
description: In a Segment Routing ISIS (SR-ISIS)/MPLS environment, on Juniper Networks Junos OS and Junos OS Evolved devices, configured with ISIS Flexible Algorithm for Segment Routing and sensor-based statistics, a flap of a ISIS link in the network, can lead to a routing process daemon (RPD) crash and restart, causing a Denial of Service (DoS). Continued link flaps will create a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS: 19.4 versions prior to 19.4R1-S4, 19.4R3-S2; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R2-S2, 20.2R3; 20.3 versions prior to 20.3R2; Juniper Networks Junos OS Evolved: 20.3-EVO versions prior to 20.3R2-EVO; 20.4-EVO versions prior to 20.4R2-EVO. This issue does not affect: Juniper Networks Junos OS releases prior to 19.4R1. Juniper Networks Junos OS Evolved releases prior to 19.4R1-EVO.
problem types: CWE-754 Improper Check for Unusual or Exceptional Conditions
affected:
{
product: Junos OS
vendor: Juniper Networks
versions:
lessThan: 19.4R1, status: unaffected, version: unspecified, versionType: custom
changes: [at: 19.4R1-S4, 19.4R3-S2, status: unaffected], lessThan: 19.4*, status: affected, version: 19.4R1, versionType: custom
lessThan: 20.1R2-S1, 20.1R3, status: affected, version: 20.1, versionType: custom
lessThan: 20.2R2-S2, 20.2R3, status: affected, version: 20.2, versionType: custom
lessThan: 20.3R2, status: affected, version: 20.3, versionType: custom
}
{
product: Junos OS Evolved
vendor: Juniper Networks
versions:
lessThan: 19.4R1-EVO, status: unaffected, version: unspecified, versionType: custom
lessThan: 19.4*, status: affected, version: 19.4R1-EVO, versionType: custom
lessThan: 20.1*, status: affected, version: 20.1R1-EVO, versionType: custom
lessThan: 20.2*, status: affected, version: 20.2R1-EVO, versionType: custom
lessThan: 20.3R2-EVO, status: affected, version: 20.3, versionType: custom
lessThan: 20.4R2-EVO, status: affected, version: 20.4, 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:
Junos OS: 19.4R1-S4, 19.4R3-S2, 20.1R2-S1, 20.1R3, 20.2R2-S2, 20.2R3, 20.3R2, 20.4R1, and all subsequent releases.
Junos OS Evolved: 20.3R2-EVO, 20.4R2-EVO, 21.1R1-EVO, and all subsequent releases.
workarounds: Disabling IS-IS Flexible Algorithm for Segment Routing or sensor-based statistics will mitigate this issue.