title: Junos OS: MX Series and SRX Series: Processing of a specific SIP packet causes NAT IP allocation to fail
description:
An Improper Validation of Syntactic Correctness of Input vulnerability in Packet Forwarding Engine (PFE) of Juniper Networks Junos OS allows an unauthenticated, network-based attacker to cause Denial of Service (DoS).
On all Junos OS MX Series and SRX Series platforms, when SIP ALG is enabled, and a specific SIP packet is received and processed, NAT IP allocation fails for genuine traffic, which causes Denial of Service (DoS). Continuous receipt of this specific SIP ALG packet will cause a sustained DoS condition.
NAT IP usage can be monitored by running the following command.
user@srx> show security nat resource-usage source-pool <source_pool_name>
Pool name: source_pool_name
..
Address Factor-index Port-range Used Avail Total Usage
X.X.X.X
0 Single Ports 50258 52342 62464 96% <<<<<
- Alg Ports 0 2048 2048 0%
This issue affects:
Juniper Networks Junos OS on MX Series and SRX Series
*  All versions earlier than 21.2R3-S6;
*  21.3 versions earlier than 21.3R3-S5;
*  21.4 versions earlier than 21.4R3-S5;
*  22.1 versions earlier than 22.1R3-S4;
*  22.2 versions earlier than 22.2R3-S3;
*  22.3 versions earlier than 22.3R3-S1;
*  22.4 versions earlier than 22.4R2-S2, 22.4R3;
*  23.2 versions earlier than 23.2R1-S1, 23.2R2.
problem types: CWE-1286: Improper Validation of Syntactic Correctness of Input
affected:
{
defaultStatus: unaffected
platforms: [MX Series, SRX Series]
product: Junos OS
vendor: Juniper Networks
versions:
lessThan: 21.2R3-S6, status: affected, version: 0, versionType: semver
lessThan: 21.3R3-S5, status: affected, version: 21.3, versionType: semver
lessThan: 21.4R3-S5, status: affected, version: 21.4, versionType: semver
lessThan: 22.1R3-S4, status: affected, version: 22.1, versionType: semver
lessThan: 22.2R3-S3, status: affected, version: 22.2, versionType: semver
lessThan: 22.3R3-S1, status: affected, version: 22.3, versionType: semver
lessThan: 22.4R2-S2, 22.4R3, status: affected, version: 22.4, versionType: semver
lessThan: 23.2R1-S1, 23.2R2, status: affected, version: 23.2, versionType: semver
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 7.5
baseSeverity: HIGH
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/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 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R2-S2, 22.4R3, 23.2R1-S1, 23.2R2, 23.4R1, and all subsequent releases.
workarounds: There are no known workarounds for this issue, but it should be considered to disable the SIP ALG if it's not strictly needed.