CVE-2026-21902

Summary

An Incorrect Permission Assignment for Critical Resource vulnerability in the On-Box Anomaly detection framework of Juniper Networks Junos OS Evolved on PTX Series allows an unauthenticated, network-based attacker to execute code as root.

The On-Box Anomaly detection framework should only be reachable by other internal processes over the internal routing instance, but not over an externally exposed port. With the ability to access and manipulate the service to execute code as root a remote attacker can take complete control of the device. Please note that this service is enabled by default as no specific configuration is required.

This issue affects Junos OS Evolved on PTX Series:

• 25.4 versions before 25.4R1-S1-EVO, 25.4R2-EVO.

This issue does not affect Junos OS Evolved versions before 25.4R1-EVO.

This issue does not affect Junos OS.

Affected Software

Weaknesses

• CWE-732: CWE-732 Incorrect Permission Assignment for Critical Resource

Workarounds

To reduce the risk of exploitation of this issue, use access lists or firewall filters to limit access to only trusted networks and hosts. Please ensure such filters only permit explicitly required connections and block all others.

Also this service can be disabled by 'request pfe anomalies disable'.

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: total

Additional References

• https://github.com/watchtowrlabs/watchTowr-vs-JunosEvolved-CVE-2026-21902/blob/main/watchTowr-vs-JunosEvolved-CVE-2026-21902.py

References

• https://supportportal.juniper.net/JSA107128
• https://kb.juniper.net/JSA107128

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