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Medium4.7Juniper Networks

Medium [CVE-2026-57031] 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

This medium-severity Juniper Networks advisory covers CVE-2026-57031 affecting Junos OS, Junos, MX.

CVE-2026-57031 Published Jul 9, 2026Updated by vendor Jul 10, 2026
CVE-2026-57031
Affected products & platforms
Juniper NetworksFirewallRoutersJunosMX / RoutersMX304
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Summary

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,

Affected products named by the advisory: MX.

Affected products named by the advisory: MX.

Affected versions
  • 23.2
  • 23.4
  • 24.2
  • 24.4
  • 25.2

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions
  • 23.2R2-S7
  • 23.4R2-S7
  • 24.2R2-S3
  • 24.4R2-S2
  • 25.2R2

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation

Upgrade to a fixed release: 23.2R2-S7, 23.4R2-S7, 24.2R2-S3, 24.4R2-S2, 25.2R2. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Discussion(0)

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