CVE-2026-33774
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.
- CVSS 4.0
- 6.9
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/AU:Y/R:U/RE:L - CVSS 3.1
- 5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 6% of CVEs (scores of 2026-10-26)
- CWE
- CWE-754
- Published
- Modified
- Record from
- the NVD, synced
Affected
- juniper:junos