High priorityDisclosed

Advisory · CVE-2026-102079

CLI command injection in Junos OS lets a low-privilege user take over MX devices

An OS command injection vulnerability in the Junos OS CLI lets a local low-privileged attacker take complete control of the device: a specific request csds command does not sanitize user input, so it can be interpreted as a command and executed with root privileges. Juniper rates it CVSS 4.0 8.5 (CVSS 3.1 7.8), affecting MX Series releases from 24.4.

Advisory published October 14, 2026Independent summary
Vendor
Juniper Networks
Product
Junos OS
Identifier / CWE
CVE-2026-102079
CWE-78
Action timing
Immediate
ELI5

Explain it like I’m five

One operational command forgets to sanitize its arguments, and a low-privilege login becomes full device control.

SIMPLIFIED_ATTACK_PATH03 STEPS
  1. 01Low-privilege CLI login

    An attacker signs in with a low-privilege Junos account on an MX device.

  2. 02request csds abused

    Input to the request csds command is not sanitized and is interpreted as a command.

  3. 03Root control

    The injected command executes with root privileges, giving complete device control.

What happened

Juniper disclosed CVE-2026-102079 in its October 2026 security release: an OS command injection vulnerability (CWE-78) in the Junos OS CLI on MX Series. The request csds command does not sanitize user-provided input, letting a local low-privileged attacker execute commands with root privileges. The vendor record lists 24.4 releases before 24.4R2-S4, 25.2 before 25.2R2-S1, and 25.4 before 25.4R1-S3 as affected, and says releases before 24.4R1 are not affected.

Juniper’s JSA112180 lists the affected service releases and the October 2026 service release thresholds that carry the fix. Match your exact release to the advisory rather than guessing here.

What to do

  1. Inventory every Junos OS deployment, including test, training, and individually managed instances.
  2. Apply the vendor fix or upgrade exactly as directed in the linked vendor bulletin or advisory.
  3. Restrict network access to Junos OS while remediation is underway, especially for internet-facing instances.
  4. Review application and server logs for request csds usage by low-privilege accounts and unexpected root-level changes following CLI sessions.
  5. Check for accounts, content, or configuration created outside normal change processes, and rotate exposed credentials where access cannot be ruled out.
  6. Verify the deployed version or patch level after remediation.

Management note

CLI access tiers only work if commands sanitize input. Patch MX devices and audit who can run operational commands.