title: MS-MPC or MS-MIC crash when passing large fragmented traffic through an ALG
description: An MS-MPC or MS-MIC Service PIC may crash when large fragmented packets are passed through an Application Layer Gateway (ALG). Repeated crashes of the Service PC can result in an extended denial of service condition. The issue can be seen only if NAT or stateful-firewall rules are configured with ALGs enabled. This issue was caused by the code change for PR 1182910 in Junos OS 14.1X55-D30, 14.1X55-D35, 14.2R7, 15.1R5, and 16.1R2. No other versions of Junos OS and no other Juniper Networks products or platforms are affected by this issue. Affected releases are Juniper Networks Junos OS on MX platforms running: 14.1X55 from 14.1X55-D30 to releases prior to 14.1X55-D35; 14.2R from 14.2R7 to releases prior to 14.2R7-S4, 14.2R8; 15.1R from 15.1R5 to releases prior to 15.1R5-S2, 15.1R6; 16.1R from 16.1R2 to releases prior to 16.1R3-S2, 16.1R4.
problem types: Denial of service
affected:
{
platforms: MX Series
product: Junos OS
vendor: Juniper Networks
versions:
status: affected, version: 14.1X55 from 14.1X55-D30 prior to 14.1X55-D35
status: affected, version: 14.2R from 14.2R7 prior to 14.2R7-S4, 14.2R8
status: affected, version: 15.1R from 15.1R5 prior to 15.1R5-S2, 15.1R6
status: affected, version: 16.1R from 16.1R2 prior to 16.1R3-S2, 16.1R4
}
metrics:
cvssV3_0: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 5.9
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.0
]
workarounds: There are no viable workarounds for this issue.
If NAT and stateful-firewall are not required, disabling them in the [edit applications] stanza will mitigate this issue.
It is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the device from trusted, administrative networks or hosts.