title: SRX series: Junos OS: SRX series using IPv6 Sun/MS-RPC ALGs may experience flowd crash on processing packets.
description: Any Juniper Networks SRX series device with one or more ALGs enabled may experience a flowd crash when traffic is processed by the Sun/MS-RPC ALGs. This vulnerability in the Sun/MS-RPC ALG services component of Junos OS allows an attacker to cause a repeated denial of service against the target. Repeated traffic in a cluster may cause repeated flip-flop failure operations or full failure to the flowd daemon halting traffic on all nodes. Only IPv6 traffic is affected by this issue. IPv4 traffic is unaffected. This issues is not seen with to-host traffic. This issue has no relation with HA services themselves, only the ALG service. No other Juniper Networks products or platforms are affected by this issue. Affected releases are Juniper Networks Junos OS 12.1X46 prior to 12.1X46-D55 on SRX; 12.1X47 prior to 12.1X47-D45 on SRX; 12.3X48 prior to 12.3X48-D32, 12.3X48-D35 on SRX; 15.1X49 prior to 15.1X49-D60 on SRX.
problem types: Denial of service
affected:
{
platforms: SRX Series
product: Junos OS
vendor: Juniper Networks
versions:
status: affected, version: 12.1X46 prior to 12.1X46-D55
status: affected, version: 12.3X48 prior to 12.3X48-D32, 12.3X48-D35
status: affected, version: 15.1X49 prior to 15.1X49-D60
}
metrics:
cvssV3_0: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 7.5
baseSeverity: HIGH
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:H
version: 3.0
]
workarounds: Disable Sun/MS-RPC ALGs on the SRX Series device.
Disable IPv6 on the device.
example:
deactivate interfaces xe-0/0/0 unit 0 family inet6 address 2000::254/64
Filtering incoming IPv6, or Sun/MS-RPC from the device is also an option.
example:
set interfaces xe-0/0/0 unit 0 family inet6 filter input TEST ==> apply to interface
set firewall family inet6 filter TEST term t1 from destination-port 135
set firewall family inet6 filter TEST term t1 then discard