Junos OS (SRX firewalls)
CVE-2025-21596: SRX1500,SRX4100,SRX4200: Execution of low-privileged CLI command results in chassisd crash
An Improper Handling of Exceptional Conditions vulnerability in the command-line processing of Juniper Networks Junos OS on SRX1500, SRX4100, and SRX4200 devices allows a local, low-privileged authenticated attacker executing the 'show chassis environment pem' command to cause the chassis daemon (chassisd) to crash and restart, resulting in a temporary Denial of Service (DoS).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS (SRX1500, SRX4100, SRX4200) 0 | 21.4R3-S9 or later |
| Junos OS (SRX1500, SRX4100, SRX4200) 22.2 | 22.2R3-S5 or later |
| Junos OS (SRX1500, SRX4100, SRX4200) 22.3 | 22.3R3-S4 or later |
| Junos OS (SRX1500, SRX4100, SRX4200) 22.4 | 22.4R3-S4 or later |
| Junos OS (SRX1500, SRX4100, SRX4200) 23.2 | 23.2R2-S3 or later |
| Junos OS (SRX1500, SRX4100, SRX4200) 23.4 | 23.4R2-S1 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Improper Handling of Exceptional Conditions vulnerability in the command-line processing of Juniper Networks Junos OS on SRX1500, SRX4100, and SRX4200 devices allows a local, low-privileged authenticated attacker executing the 'show chassis environment pem' command to cause the chassis daemon (chassisd) to crash and restart, resulting in a temporary Denial of Service (DoS). However, repeated execution of this command will eventually cause the chassisd process to fail to restart, impacting packet processing on the system.
This issue affects Junos OS on SRX1500, SRX4100, SRX4200:
- All versions before 21.4R3-S9,
- from 22.2 before 22.2R3-S5,
- from 22.3 before 22.3R3-S4,
- from 22.4 before 22.4R3-S4,
- from 23.2 before 23.2R2-S3,
- from 23.4 before 23.4R2-S1.
Workarounds
Use access lists or firewall filters to limit access to the CLI only from trusted hosts and administrators.
Utilize CLI authorization to disallow execution of the 'show chassis environment pem' command.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.