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CVE-2026-57020

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

MEDIUM
6.5
CVSS Score
Published: July 9, 2026 at 09:05 PM UTC
Updated: October 25, 2026 at 03:10 PM UTC
1 product affected across 1 vendorJunos· also runs on 2 platforms

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos· Juniper Networks
95%
v < 23.223.223.2 r123.2 r1-s123.2 r1-s223.2 r223.2 r2-s123.2 r2-s223.2 r2-s323.2 r2-s423.2 r2-s523.2 r2-s623.423.4 r123.4 r1-s123.4 r1-s223.4 r223.4 r2-s123.4 r2-s223.4 r2-s323.4 r2-s423.4 r2-s523.4 r2-s623.4 r2-s724.224.2 r124.2 r1-s124.2 r1-s224.2 r224.2 r2-s124.2 r2-s224.2 r2-s324.424.4 r124.4 r1-s224.4 r1-s324.4 r224.4 r2-s124.4 r2-s224.4 r2-s3
Affected range stops below 23.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 23.2R2-S7, so it looks safe — our inference, not a vendor statement
Affected range stops below 23.4R2-S8, so it looks safe — our inference, not a vendor statement
Affected range stops below 24.2R2-S4, so it looks safe — our inference, not a vendor statement
Affected range stops below 24.4R2-S4, so it looks safe — our inference, not a vendor statement
juniper-qfx10008 (environment) · juniper-qfx10016 (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisory
Source: cverecord
https://supportportal.juniper.net/JSA110080

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMjuniper
Attack Vector
ADJACENT_NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-754

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