CVE-2026-57031: MX Series: For subscribers configured on static interfaces, input filters are not in effect

Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.

Affected and fixed versions

Product / branch	Fixed in
Junos OS (MX Series) 23.2R2-S1	23.2R2-S7 or later
Junos OS (MX Series) 23.4R2	23.4R2-S7 or later
Junos OS (MX Series) 24.2	24.2R2-S3 or later
Junos OS (MX Series) 24.4	24.4R2-S2 or later
Junos OS (MX Series) 25.2	25.2R2 or later

Always confirm against the vendor advisory, which lists every fixed hotfix.

What it is

An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters.

On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect.

This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304:

23.2 versions from 23.2R2-S1 before 23.2R2-S7,
23.4 versions from 23.4R2 before 23.4R2-S7,
24.2 versions before 24.2R2-S3,
24.4 versions before 24.4R2-S2,
25.2 versions before 25.2R2.

Am I affected?

To be exposed to this issue a configuration for static subscribers with an input filter is required:

[ system services static-subscribers ]

[ dynamic-profiles <profile-name> interfaces <interface> unit <unit> family (inet|inet6) filter input <filter-name> ]

Workarounds

There are no known workarounds for this issue.

Exploitation

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.