Unchecked Input Loop Vulnerability in Junos OS on MX Series by Juniper Networks
CVE-2026-33800

7.1HIGH

Key Information:

Vendor

Juniper Networks
Status
Junos Os
Vendor
CVE Published:
9 July 2026

Badges

👾 Exploit Exists

What is CVE-2026-33800?

An unchecked input vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks' Junos OS for MX Series routers allows unauthenticated attackers in adjacent networks to trigger a Denial-of-Service (DoS). This occurs during repeated micro-BFD session flaps, overwhelming the PFEMAN process with queued events. In scenarios utilizing locality-bias in Virtual-Chassis configurations, the processing time for each event significantly increases. The persistent flapping results in the PFEMAN watchdog timer expiring, causing a full crash and restart of the Forwarding Platform Card (FPC), disrupting service and impacting network reliability.

Affected Version(s)

Junos OS MX Series 0 < 23.2R2-S7

Junos OS MX Series 23.4 < 23.4R2-S8

Junos OS MX Series 24.2 < 24.2R2-S4

References

https://supportportal.juniper.net/JSA110075
vendor-advisory

CVSS V4

Score:
7.1
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Adjacent Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

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