CVE-2026-57020: 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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Juniper Networks Junos OS on QFX10000 Seriesto a version that resolves this vulnerability.Fixed in 23.2R2-S7 - Upgrade
Upgrade
Juniper Networks Junos OS on QFX10000 Seriesto a version that resolves this vulnerability.Fixed in 23.4R2-S8 - Upgrade
Upgrade
Juniper Networks Junos OS on QFX10000 Seriesto a version that resolves this vulnerability.Fixed in 24.2R2-S4 - Upgrade
Upgrade
Juniper Networks Junos OS on QFX10000 Seriesto a version that resolves this vulnerability.Fixed in 24.4R2-S4
Event History
Frequently Asked Questions
What is the severity of CVE-2026-57020?
The severity of CVE-2026-57020 is rated as high with a score of 7.1.
How does CVE-2026-57020 affect Junos OS on QFX10000 Series devices?
CVE-2026-57020 allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS) via IPv6 multicast traffic received on non-IRB interfaces.
What is the risk associated with CVE-2026-57020?
CVE-2026-57020 has a risk rating of 40, indicating a significant threat to the affected systems.
Can CVE-2026-57020 be exploited remotely?
No, exploitation of CVE-2026-57020 requires an adjacent attacker, which limits remote exploitation.
What is the recommended mitigation for CVE-2026-57020?
To mitigate CVE-2026-57020, it is advised to follow official vendor guidance on updating or configuring Junos OS on QFX10000 devices.