An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS on MX Series allows an unauthenticated network-based attacker to send specific packets to an Aggregated Multiservices (AMS) interface on the device, causing the packet forwarding engine (PFE) to crash, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition.
 

This issue is only triggered by packets destined to a local-interface via a service-interface (AMS). AMS is only supported on the MS-MPC, MS-MIC, and MX-SPC3 cards. This issue is not experienced on other types of interfaces or configurations. Additionally, transit traffic does not trigger this issue.

This issue affects Juniper Networks Junos OS on MX Series:

• All versions prior to 19.1R3-S10;
• 19.2 versions prior to 19.2R3-S7;
• 19.3 versions prior to 19.3R3-S8;
• 19.4 versions prior to 19.4R3-S12;
• 20.2 versions prior to 20.2R3-S8;
• 20.4 versions prior to 20.4R3-S7;
• 21.1 versions prior to 21.1R3-S5;
• 21.2 versions prior to 21.2R3-S5;
• 21.3 versions prior to 21.3R3-S4;
• 21.4 versions prior to 21.4R3-S3;
• 22.1 versions prior to 22.1R3-S2;
• 22.2 versions prior to 22.2R3;
• 22.3 versions prior to 22.3R2-S1, 22.3R3;
• 22.4 versions prior to 22.4R1-S2, 22.4R2.

A sample next-hop-service interface configuration is shown below:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2023-36832.
 

The following software releases have been updated to resolve this specific issue: 19.1R3-S10, 19.2R3-S7, 19.3R3-S8, 19.4R3-S12, 20.2R3-S8, 20.4R3-S7, 21.1R3-S5, 21.2R3-S5, 21.3R3-S4, 21.4R3-S3, 22.1R3-S2, 22.2R3, 22.3R2-S1, 22.3R3, 22.4R1-S2, 22.4R2, 23.1R1, and all subsequent releases.

This issue is being tracked as 1707140

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
 

2023-07-12: Initial Publication

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2023-36832 at www.cve.org
• https://kb.juniper.net/JSA71639 [juniper.net]