CVE-2026-57020 PUBLISHED

Junos OS: QFX10000 Series: IPv6 multicast traffic received on non-IRB interfaces causes a multicast flood

Assigner: juniper
Reserved: 23.06.2026 Published: 09.07.2026 Updated: 10.07.2026

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.

Metrics

CVSS Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:U/RE:M
CVSS Score: 7.1

Product Status

Vendor Juniper Networks
Product Junos OS
Versions Default: unaffected
  • affected from 0 to 23.2R2-S7 (excl.)
  • affected from 23.4 to 23.4R2-S8 (excl.)
  • affected from 24.2 to 24.2R2-S4 (excl.)
  • affected from 24.4 to 24.4R2-S4 (excl.)

Exploits

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

Workarounds

There are no known workarounds for this issue.

Solutions

The following software releases have been updated to resolve this specific issue:

Junos OS: 23.2R2-S7, 23.4R2-S8, 24.2R2-S4, 24.4R2-S4.

References

Problem Types

  • CWE-754 Improper Check for Unusual or Exceptional Conditions CWE