CVE-2026-57020
published 2026-07-09CVE-2026-57020: An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on QFX10000 Series…
PriorityP433medium6.5CVSS 3.1
AVAACLPRNUINSUCNINAH
EPSS
0.27%
18.7th percentile
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
44 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| juniper | junos | < 23.2 | 23.2 |
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CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv4.07.1HIGHCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:X/RE:M/U:X
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VulDB
Juniper Junos OS up to 23.2R2-S6/23.4R2-S7/24.2R2-S3/24.4R2-S3 Packet Forwarding Engine infinite loop
vuldb·2026-07-10·CVSS 6.5
CVE-2026-57020 [MEDIUM] Juniper Junos OS up to 23.2R2-S6/23.4R2-S7/24.2R2-S3/24.4R2-S3 Packet Forwarding Engine infinite loop
A vulnerability was found in Juniper Junos OS up to 23.2R2-S6/23.4R2-S7/24.2R2-S3/24.4R2-S3 and classified as critical. Affected is an unknown function of the component Packet Forwarding Engine. Executing a manipulation can lead to infinite loop.
This vulnerability is tracked as CVE-2026-57020. The attack can be launched remotely. No exploit exists.
GHSA
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
ghsa_unreviewed·2026-07-10
CVE-2026-57020 [HIGH] CWE-754 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
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 24.2R
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-07-09
Published