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.
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> ]
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
There are no known workarounds for this issue.
The following software releases have been updated to resolve this specific issue:
Junos OS: 23.2R2-S7, 23.4R2-S8, 24.2R2-S5, 24.4R2-S4, 25.2R2-S1, 25.4R1-S2, 25.4R2, 26.2R1, and all subsequent releases.