CVE-2026-102177 Juniper Networks CVE debrief

Who should care

Network administrators and security teams responsible for managing Junos OS and Junos OS Evolved systems should assess exposure and prioritize patching to prevent potential denial-of-service attacks.

Why it matters

CVE-2026-102177 is a high-severity vulnerability in Junos OS and Junos OS Evolved that can cause a denial of service when IS-IS link protection and backup-selection are configured. Network administrators and security teams should prioritize patching affected systems to prevent potential attacks.

• Denial of service attacks may occur if vulnerable systems are not patched
• Network availability and stability may be impacted if adjacent unauthenticated attackers exploit the vulnerability
• Security teams should verify IS-IS link protection and backup-selection configurations to prevent exploitation
• Patching affected systems is crucial to prevent potential attacks

Technical summary

An out-of-bounds write vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent unauthenticated attacker to cause a denial of service when IS-IS link protection and backup-selection are configured. The vulnerability affects Junos OS and Junos OS Evolved systems, and network administrators and security teams should prioritize patching affected systems to prevent potential denial-of-service attacks. The vulnerability has a high severity score and can cause significant impact if exploited.

Defensive priority

Network administrators and security teams should prioritize patching affected Junos OS and Junos OS Evolved systems to prevent potential denial-of-service attacks.

Recommended defensive actions

• Patch affected Junos OS and Junos OS Evolved systems
• Verify IS-IS link protection and backup-selection configurations
• Monitor for potential denial-of-service attacks
• 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 record and NVD vulnerability detail page provide information on the vulnerability, but do not offer additional context on exploitation or impact. The source item providing details on the vulnerability also lacks information on potential attacks or affected systems. Limited evidence is available, and defenders should verify IS-IS link protection and backup-selection configurations to prevent exploitation.

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.