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

Medium 5.3 Published 9 Jul 2026 Updated 10 Jul 2026

Adjacent subscribers can bypass ingress firewall filters and bandwidth limits on specific Juniper MX Series configurations.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-57031?

CVE-2026-57031 is a medium-severity vulnerability in Juniper Junos, published on 9 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-754

Which versions are affected by CVE-2026-57031?

It affects 1 product.

Products include Juniper Junos.

How do I fix CVE-2026-57031?

No fix has been published for CVE-2026-57031 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-57031 being exploited?

There is no known exploitation of CVE-2026-57031 in the wild and no public exploit code.

All Juniper Junos vulnerabilities

Sources

Also known as GHSA-7v7x-35fg-5xc8.