A NULL Pointer Dereference vulnerability in the flow daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an attacker causing specific, valid control traffic to be sent out of a Dual-Stack (DS) Lite tunnel to crash the flowd process, resulting in a Denial of Service (DoS).  Continuous triggering of specific control traffic will create a sustained Denial of Service (DoS) condition.

On all SRX platforms, when specific, valid control traffic needs to be sent out of a DS-Lite tunnel, a segmentation fault occurs within the flowd process, resulting in a network outage until the flowd process restarts.

This issue affects Junos OS on SRX Series:

• All versions before 21.2R3-S9,
• from 21.4 before 21.4R3-S9,
• from 22.2 before 22.2R3-S5,
• from 22.4 before 22.4R3-S6,
• from 23.2 before 23.2R2-S3,
• from 23.4 before 23.4R2.

Exploitation of this issue requires DS-Lite tunneling to be configured on the SRX Series device:

[ security softwires softwire-name <name> softwire-concentrator ...]

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

This issue was found during internal product security testing or research.

The following software releases have been updated to resolve this specific issue: Junos OS 21.2R3-S9, 21.4R3-S9, 22.2R3-S5, 22.4R3-S6, 23.2R2-S3, 23.4R2, 24.2R1, and all subsequent releases.

This issue is being tracked as 1779792 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).

There are no known workarounds for this issue.

2025-04-09: Initial Publication
2025-04-24: Corrected configuration example for SRX Series

• 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