CVE-2026-101966 Juniper Networks CVE debrief

Who should care

Network administrators, security teams, and IT professionals managing Junos OS Evolved installations should assess exposure and prioritize remediation. This includes reviewing the current version of Junos OS Evolved, verifying potential mitigations, and applying patches or updates as recommended by Juniper Networks.

Why it matters

CVE-2026-101966 is a high-severity vulnerability in Junos OS Evolved that can cause denial of service to the telemetry dial-out daemon. Network administrators and security teams should prioritize verification of exposure and remediation, especially those managing Junos OS Evolved installations.

• Denial of service to telemetry dial-out daemon
• Potential disruption to network monitoring and management
• Need for verification of Junos OS Evolved version and exposure
• Remediation priority for affected installations

Technical summary

A Use of Externally-Controlled Format String vulnerability in the jti-dialoutd of Juniper Networks Junos OS Evolved allows an authenticated network attacker to cause persistent telemetry dial-out denial of service via a crafted analytics sensor resource submitted through gNMI listener. The vulnerability affects various versions of Junos OS Evolved, including those prior to 25.4R1-S3-EVO, 26.2R1-S2-EVO, 25.2X100-D35-EVO, and 25.4X300-D40-EVO. Network administrators and security teams should prioritize verification of exposure and remediation.

Defensive priority

Network administrators and security teams should prioritize verification of exposure and remediation, especially those managing Junos OS Evolved installations.

Recommended defensive actions

• Verify Junos OS Evolved version and check for exposure
• Apply patches or updates as recommended by Juniper Networks
• Monitor telemetry dial-out daemon for unusual activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE Program and NVD provide official records of this vulnerability. Juniper Networks also provides a vendor advisory (JSA112250) for this issue. The vulnerability has been verified to exist in various versions of Junos OS Evolved, including those prior to 25.4R1-S3-EVO, 26.2R1-S2-EVO, 25.2X100-D35-EVO, and 25.4X300-D40-EVO. However, the exact scope of affected systems and potential mitigations are still being investigated.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.