title: Junos OS: PTX Series: In an FTI scenario MPLS packets hitting reject next-hop will cause a host path wedge condition
description:
An Improper Neutralization of Equivalent Special Elements vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on PTX Series allows a unauthenticated, adjacent attacker to cause a Denial of Service (DoS).
When MPLS packets are meant to be sent to a flexible tunnel interface (FTI) and if the FTI tunnel is down, these will hit the reject NH, due to which the packets get sent to the CPU and cause a host path wedge condition. This will cause the FPC to hang and requires a manual restart to recover.
Please note that this issue specifically affects PTX1000, PTX3000, PTX5000 with FPC3, PTX10002-60C, and PTX10008/16 with LC110x. Other PTX Series devices and Line Cards (LC) are not affected.
The following log message can be seen when the issue occurs:
Cmerror Op Set: Host Loopback: HOST LOOPBACK WEDGE DETECTED IN PATH ID <id> (URI: /fpc/<fpc>/pfe/<pfe>/cm/<cm>/Host_Loopback/<cm>/HOST_LOOPBACK_MAKE_CMERROR_ID[<id>])
This issue affects Juniper Networks Junos OS:
*  All versions earlier than 20.4R3-S8;
*  21.1 versions earlier than 21.1R3-S4;
*  21.2 versions earlier than 21.2R3-S6;
*  21.3 versions earlier than 21.3R3-S3;
*  21.4 versions earlier than 21.4R3-S5;
*  22.1 versions earlier than 22.1R2-S2, 22.1R3;
*  22.2 versions earlier than 22.2R2-S1, 22.2R3.
problem types: CWE-76 Improper Neutralization of Equivalent Special Elements
affected:
{
defaultStatus: unaffected
platforms: [PTX1000, PTX3000, PTX5000 with FPC3, PTX10002-60C, PTX10008/16 with LC110x]
product: Junos OS
vendor: Juniper Networks
versions:
lessThan: 20.4R3-S8, status: affected, version: 0, versionType: semver
lessThan: 21.1R3-S4, status: affected, version: 21.1, versionType: semver
lessThan: 21.2R3-S6, status: affected, version: 21.2, versionType: semver
lessThan: 21.3R3-S3, status: affected, version: 21.3, versionType: semver
lessThan: 21.4R3-S5, status: affected, version: 21.4, versionType: semver
lessThan: 22.1R2-S2, 22.1R3, status: affected, version: 22.1, versionType: semver
lessThan: 22.2R2-S1, 22.2R3, status: affected, version: 22.2, versionType: semver
}
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
]
format: CVSS
scenarios: GENERAL
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 20.4R3-S8, 21.1R3-S4, 21.2R3-S6, 21.3R3-S3, 21.4R3-S5, 22.1R2-S2, 22.1R3, 22.2R2-S1, 22.2R3, 22.3R1, and all subsequent releases.
workarounds: The issue can be prevented by configuring a limit for reject packets via:
[ system ddos-protection protocols reject aggregate bandwidth 20 ]