CVE-2026-57054: MX Series: Web filtering doesn't block specifically formatted URLs

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) 0	23.2R2-S7 or later
Junos OS (MX Series) 23.4	23.4R2-S8 or later
Junos OS (MX Series) 24.2	24.2R2-S5 or later
Junos OS (MX Series) 24.4	24.4R2-S4 or later
Junos OS (MX Series) 25.2	25.2R2-S1 or later
Junos OS (MX Series) 25.4	25.4R1-S2, 25.4R2 or later

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

What it is

A Use of Incorrectly-Resolved Name or Reference vulnerability in the URL filtering plugin of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to bypass web filtering and access downstream resources that should be unreachable.

If an MX Series device is configured with web filtering, and an attacker sends a request with a specifically formatted URL, this request will get forwarded despite the system being configured to block it. In turn, an attacker can access downstream resources that are expected to be unreachable.

This issue affects Junos OS on MX Series:

all versions before 23.2R2-S7,
23.4 versions before 23.4R2-S8,
24.2 versions before 24.2R2-S5,
24.4 versions before 24.4R2-S4,
25.2 versions before 25.2R2-S1,
25.4 versions before 25.4R1-S2, 25.4R2.

Am I affected?

To be exposed to this issue an MX Series device needs to be configured to filter specific URLs as follows:

[ services service-set <set-name> web-filter-profile <profile-name> ] [ services web-filter profile <profile-name> url-filter-template <template-name> url-filter-database <file-with-URLs-to-filter> ]

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.