Vulnerability · Published Jul 9, 2026 · Assigned by juniper

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

Medium 4.7

In plain English

A medium-severity security flaw in Junos OS from Juniper Networks. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities).

Severity (CVSS 3.1)4.7Medium

Exploit odds (30 days)0.2%top 87.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
Juniper Networks	Junos OS	23.2R2-S1 – before 23.2R2-S723.4R2 – before 23.4R2-S724.2 – before 24.2R2-S324.4 – before 24.4R2-S225.2 – before 25.2R2

Weakness: CWE-754 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

References

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