CVE-2026-57020 Junos OS: QFX10000 Series: IPv6 multicast traffic received on non-IRB interfaces causes a multicast flood
An unauthenticated adjacent attacker can cause a denial of service by sending IPv6 multicast traffic to non-IRB interfaces on QFX10000 switches in EVPN-VxLAN scenarios.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-57020?
CVE-2026-57020 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-754
Which versions are affected by CVE-2026-57020?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2026-57020?
No fix has been published for CVE-2026-57020 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-57020 being exploited?
There is no known exploitation of CVE-2026-57020 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-vhf9-x75x-qgv5.