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.

Juniper Networks, Inc. AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Juniper Networks, Inc. CWE-1286

Juniper Networks, Inc. https://supportportal.juniper.net/JSA75757 [No types assigned]

Juniper Networks, Inc. https://www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N [No types assigned]