An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, network-based attacker to bypass the configured firewall filter and access the control-plane of the device.
On MX platforms with
MPC10, MPC11, LC4800 or LC9600
line cards, and MX304, firewall filters applied on a loopback interface lo0.n (where n is a non-0 number) don't get executed when lo0.n is in the global VRF / default routing-instance.
An affected configuration would be:
user@host# show configuration interfaces lo0 | display set
set interfaces lo0 unit 1 family inet filter input <filter-name>
where a firewall filter is applied to a non-0 loopback interface, but that loopback interface is not referred to in any routing-instance (RI) configuration, which implies that it's used in the default RI.
The issue can be observed with the CLI command:
user@device> show firewall counter filter <filter_name>
not showing any matches.
This issue affects Junos OS on MX Series:
* all versions before 23.2R2-S6,
* 23.4 versions before 23.4R2-S7,
* 24.2 versions before 24.2R2,
* 24.4 versions before 24.4R2.
References
| Link | Resource |
|---|---|
| https://kb.juniper.net/JSA107865 | Vendor Advisory |
Configurations
Configuration 1 (hide)
| AND |
|
History
08 Jul 2026, 03:20
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:o:juniper:junos:23.2:r2-s5:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:* cpe:2.3:h:juniper:mpc11:-:*:*:*:*:*:*:* cpe:2.3:h:juniper:lc4800:-:*:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:* cpe:2.3:h:juniper:mx304:-:*:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s3:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s6:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s4:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:* cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:* cpe:2.3:h:juniper:mpc10:-:*:*:*:*:*:*:* cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.4:r2-s5:*:*:*:*:*:* cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:* |
|
| References | () https://kb.juniper.net/JSA107865 - Vendor Advisory | |
| First Time |
Juniper mpc11
Juniper junos Juniper lc4800 Juniper mx304 Juniper mpc10 Juniper |
09 Apr 2026, 22:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-09 22:16
Updated : 2026-07-08 03:20
NVD link : CVE-2026-33774
Mitre link : CVE-2026-33774
CVE.ORG link : CVE-2026-33774
JSON object : View
Products Affected
juniper
- junos
- lc4800
- mpc10
- mx304
- mpc11
CWE
CWE-754
Improper Check for Unusual or Exceptional Conditions