Improper Check in Junos OS Affects Juniper Networks MX Series Devices
CVE-2026-57031

5.3MEDIUM

Key Information:

Vendor

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

Badges

👾 Exploit Exists

What is CVE-2026-57031?

A vulnerability exists in the packet forwarding engine (PFE) of Juniper Networks Junos OS, which affects MX Series devices. This security flaw allows adjacent subscribers to bypass configured firewall filters on devices running specified versions of the OS. As a result, ingress firewall filters that should enforce protocol level and upstream bandwidth limitations may not be applied, leaving the system potentially exposed. This issue impacts MX Series devices including those with MPC10/11, LC4800/9600, and MX304, specifically in certain version ranges.

Affected Version(s)

Junos OS MX Series 23.2R2-S1 < 23.2R2-S7

Junos OS MX Series 23.4R2 < 23.4R2-S7

Junos OS MX Series 24.2 < 24.2R2-S3

References

https://supportportal.juniper.net/JSA110091
vendor-advisory

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
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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