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JunosOperating system · Juniper

CVE-2025-21596

MEDIUM · 5.5 CVSS v3.1 Published 2025-01-09
Fix available
A fix is available. Upgrade to 21.4 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A command-line processing vulnerability in Junos OS on SRX1500, SRX4100, and SRX4200 devices allows a low-privileged local attacker to trigger improper exception handling in the chassis daemon (chassisd) by executing the 'show chassis environment pem' command. This causes repeated daemon crashes and restarts, ultimately leading to permanent failure of the chassisd process and packet processing disruption.

MitigationUpgrade Junos OS to a fixed version (21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S4, 23.2R2-S3, or 23.4R2-S1) per the vendor advisory. Until then, restrict CLI access to trusted personnel only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:< 21.4= 21.4= 22.2= 22.3= 22.4= 23.2= 23.4

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Run 'show chassis hardware' or 'show system information' to confirm the device is an SRX1500, SRX4100, or SRX4200
    Affected if Device model is NOT one of SRX1500, SRX4100, or SRX4200 - the vulnerability does not apply
  2. Check Junos OS version
    Run 'show version' to obtain the installed Junos OS version and compare it against the affected ranges: < 21.4, 21.4, 22.2, 22.3, 22.4, 23.2, or 23.4
    Affected if The installed version matches any of the affected versions listed (including all versions below 21.4)
  3. Verify CLI access exists
    Confirm that low-privileged users have access to the Junos CLI and can execute operational commands
    Affected if Untrusted or low-privileged users have CLI access - they can trigger the flaw by running 'show chassis environment pem'
  4. Check for chassisd crash symptoms
    Review system logs (syslog) or run 'show system core-dumps' and 'show log messages' for chassisd crash entries, or use 'request support information' to look for daemon restart patterns
    Affected if Repeated chassisd crashes or restarts are observed in logs, indicating the vulnerability may have been triggered

You are affected if your device is an SRX1500, SRX4100, or SRX4200 running any Junos version that matches < 21.4, 21.4, 22.2, 22.3, 22.4, 23.2, or 23.4, AND untrusted users can access the CLI to run the 'show chassis environment pem' command.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 21.4 or later
Fixed in 21.4
Interim mitigation

Upgrade Junos OS to a fixed version (21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S4, 23.2R2-S3, or 23.4R2-S1) per the vendor advisory. Until then, restrict CLI access to trusted personnel only.

Recommended fix High confidence

Any of: 21.4R3-S9 or later, 22.2R3-S5 or later, 22.3R3-S4 or later, 22.4R3-S4 or later, 23.2R2-S3 or later, 23.4R2-S1 or later

  1. 1. Identify the current Junos OS version by running 'show version' in the CLI
  2. 2. Review the installed configuration and verify backup of current configuration
  3. 3. Download the appropriate fixed Junos OS release from Juniper Networks support portal based on your current branch
  4. 4. Transfer the upgrade package to the device using 'file copy' or appropriate file transfer method
  5. 5. Initiate the software upgrade using 'request system software add <package-name>' command
  6. 6. Reboot the device after upgrade completes using 'request system reboot'
  7. 7. After reboot, verify the new Junos version is installed using 'show version'
  8. 8. Verify the chassis daemon is running properly using 'show chassis environment pem' and checking process status
Caveat Standard Junos upgrade risks apply: verify configuration compatibility, plan maintenance window as upgrade causes system reboot and temporary packet processing interruption

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-21596 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data