Juniper QFX10000 PFE IPv6 Mcast DoS (before 23.2R2-S7)
CVE-2026-57020 Published on July 9, 2026
Junos OS: QFX10000 Series: IPv6 multicast traffic received on non-IRB interfaces causes a multicast flood
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,
* 24.2 versions before 24.2R2-S4,
* 24.4 versions before 24.4R2-S4.
This issue does not affect Junos version after 24.4 as the QFX10000 Series devices are not supported on newer versions anymore.
Vulnerability Analysis
Weakness Type
Improper Check for Unusual or Exceptional Conditions
The software does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the software.
Products Associated with CVE-2026-57020
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Affected Versions
Juniper Networks Junos OS:- Before 23.2R2-S7 is affected.
- Version 23.4 and below 23.4R2-S8 is affected.
- Version 24.2 and below 24.2R2-S4 is affected.
- Version 24.4 and below 24.4R2-S4 is affected.