PT-2026-31798 · Juniper Networks · Mx Series+1

CVE-2026-33774 · Published 2026-04-09 · Updated 2026-07-08

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions Juniper Networks Junos OS on MX Series versions prior to 23.2R2-S6 Juniper Networks Junos OS on MX Series versions 23.4 before 23.4R2-S7 Juniper Networks Junos OS on MX Series versions 24.2 before 24.2R2 Juniper Networks Junos OS on MX Series versions 24.4 before 24.4R2

Description A flaw exists in the packet forwarding engine (pfe) of Juniper Networks Junos OS on MX Series that allows an unauthenticated, network-based attacker to bypass configured firewall filters and access the control-plane of the device. This occurs when firewall filters are applied on a loopback interface lo0.n (where n is a non-0 number) and that loopback interface is in the global VRF / default routing-instance. The issue is observed when the firewall counter for the filter does not show any matches.

Recommendations Update to Junos OS version 23.2R2-S6 or later. Update to Junos OS version 23.4R2-S7 or later. Update to Junos OS version 24.2R2 or later. Update to Junos OS version 24.4R2 or later.

Fix

DoS

Improper Check for Exceptional Conditions

Weakness Enumeration

CWE-754

Related Identifiers

CVE-2026-33774

Affected Products

Junos

Mx Series

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-33774 · Security Note
• https://kb.juniper.net/JSA107865 · Vendor Advisory
• https://t.me/cveNotify/190779 · Telegram Post
• https://twitter.com/CVEnew/status/2042364295359410596 · Twitter Post