Improper Check for Unusual or Exceptional Conditions in Junos OS - CVE-2026-33774
Published: May 8, 2026
Vulnerability identifier: #VU130691
CSH Severity: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-33774
CWE-ID: CWE-754
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Junos OS
Junos OS
Software vendor:
Juniper Networks, Inc.
Juniper Networks, Inc.
Description
The vulnerability allows a remote attacker to bypass the configured firewall filter and access the control-plane of the device.
The vulnerability exists due to improper check for unusual or exceptional conditions in the packet forwarding engine (pfe) when processing traffic to a loopback interface lo0.n in the default routing instance. A remote attacker can send network traffic to bypass the configured firewall filter and access the control-plane of the device.
Only MX Series devices with MPC10, MPC11, LC4800 or LC9600 line cards, and MX304 are affected when a firewall filter is applied to a non-0 loopback interface that is not referred to in any routing-instance configuration.
Remediation
Install security update from vendor's website.