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Advisory severityMedium6.5Juniper Networks

Medium [CVE-2026-57020] Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on QFX10000 Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS)

This medium-severity Juniper Networks advisory covers CVE-2026-57020; related products: Junos OS, Junos.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-57020 Source published Source updated

VulniPulse record published Record updated

CVE-2026-57020
Related products & platforms
Juniper NetworksSwitchesJunos
Open source advisory

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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 QFX10000 Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).

On all QFX10000 platforms in an EVPN-VxLAN scenario, if an attacker sends IPv6 multicast traffic and these packets reach the non-IRB interface of a spine switch it floods the packet to other spines and all Ethernet Segment Identifier (ESI) leaf switches.

This flooding causes the packet to be forwarded in a endless loop, which can lead to saturation of the involved links and in turn impact to legitimate traffic.

This issue affects Junos OS on QFX10000 Series:

  • all versions before 23.2R2-S7,
  • 23.4 versions before 23.4R2-S8,
Affected versions
  • * all versions before 23

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Fixed versions
  • 23.2R2-S7
  • 23.4R2-S8
  • 24.2R2-S4
  • 24.4R2-S4

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Mitigation

Upgrade to a fixed release: 23.2R2-S7, 23.4R2-S8, 24.2R2-S4, 24.4R2-S4. 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 3 months ago·verify at source

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