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CVE-2026-33774

6.9 medium SSVC exploitation: none Analyzed
NVD · CVE.org

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.

Fix

Patch, vendor advisory and mitigation references on NVD 1

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

  1. First seenCVSS 6.9 · juniperNVD modified 2026-10-26 21:10

Affected (CPE criteria) 26

  • cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.2:r2-s5:*:*:*:*:*:*
  • 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:23.4:r1-s2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
  • 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:23.4:r2-s3:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.4:r2-s4:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.4:r2-s5:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:23.4:r2-s6:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*
  • cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*

References 1