CVE-2026-102080 Juniper Networks CVE debrief

Who should care

Defenders responsible for Juniper Networks MX Series devices with SCBE3, particularly those managing network infrastructure with Junos OS, should assess exposure and apply patches to prevent potential Denial-of-Service (DoS) attacks.

Why it matters

CVE-2026-102080 is a Denial-of-Service (DoS) vulnerability in Juniper Networks Junos OS on MX Series devices. Defenders should verify exposure, prioritize patching, and monitor for unusual activity to prevent potential service disruptions.

• Potential for persistent RE switchovers and service disruption
• Need for verification of affected versions and exposure
• Priority for applying patches to prevent potential DoS attacks
• Importance of monitoring for unusual RE switchover patterns and clksyncd process crashes

Technical summary

An Improper Resource Locking vulnerability in the clock synchronization daemon (clksyncd) of Juniper Networks Junos OS on MX Series allows a unauthenticated, logically adjacent attacker to cause a Denial-of-Service (DoS). If a SyncE or PTP upstream node sends a malformed message to an MX device equipped with SCBE3, a false 19.44MHz alarm is generated on the master RE. This leads to persistent RE switchovers and a clksyncd process crash.

Defensive priority

Defenders should prioritize verifying exposure and applying vendor patches, focusing on MX Series devices with SCBE3 and assessing inventory for affected versions.

Recommended defensive actions

• Verify MX Series devices with SCBE3 for affected Junos OS versions
• Apply patches for affected versions: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S4, 25.2R2-S1, 25.4R1-S2
• Monitor for unusual RE switchover patterns and clksyncd process crashes
• Review and update inventory for MX Series devices with SCBE3
• Track exceptions and retest remediated assets
• 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

Evidence notes

The CVE record and source item provide details on the vulnerability, affected versions, and potential impact. However, specific details on exploitation or victim organizations are not provided. Defenders should verify exposure by reviewing inventory for MX Series devices with SCBE3 and assessing affected Junos OS versions. The source item and CVE record provide evidence of the vulnerability's existence and its potential impact on network infrastructure.

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.