An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on SRX Series, and MX Series with SPC3 allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).

When an affected device receives specific valid TCP traffic, the pfe crashes and restarts leading to a momentary but complete service outage.
 

This issue affects Junos OS:

21.2 releases from 21.2R3-S5 before 21.2R3-S6.

This issue does not affect earlier or later releases.

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

This issue was seen during production usage.

The following software releases have been updated to resolve this specific issue: 21.2R3-S6.
 

This issue is being tracked as 1733627 which is visible on the Customer Support website.
 

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

2024-07-10: Initial Publication
2024-09-13: Minor formatting change to CVSS field

• 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
• https://www.cve.org/CVERecord?id=CVE-2024-39540