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Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on MX Series allows adjacent subscribers to bypass configured firewall filters. On MX Series devices with MPC10/11, LC4800/9600, and MX304 with subscribers configured on static interfaces, ingress firewall filters are not enforced, so that neither protocol level nor upstream bandwidth limitation are in effect. This issue affects Junos OS on MX with MPC10/11, LC4800/9600/4802, and MX304: * 23.2 versions from 23.2R2-S1 before 23.2R2-S7, * 23.4 versions from 23.4R2 before 23.4R2-S7, * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S2, * 25.2 versions before 25.2R2.

PUBLISHED Reserved 2026-06-23 | Published 2026-07-09 | Updated 2026-07-10 | Assigner juniper




MEDIUM: 4.7CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

MEDIUM: 5.3CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/AU:Y/RE:M

Problem types

CWE-754 Improper Check for Unusual or Exceptional Conditions

Product status

Default status
unaffected

23.2R2-S1 (custom) before 23.2R2-S7
affected

23.4R2 (custom) before 23.4R2-S7
affected

24.2 (custom) before 24.2R2-S3
affected

24.4 (custom) before 24.4R2-S2
affected

25.2 (custom) before 25.2R2
affected

References

supportportal.juniper.net/JSA110091 vendor-advisory

cve.org (CVE-2026-57031)

nvd.nist.gov (CVE-2026-57031)

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