CVE-2026-21910

HIGH EPSS 16.1%
Published Jan 15, 20265mo ago · Modified Jun 17, 20262w ago
7.1 CVSS 4.0
High
Find Similar
Published Jan 15, 2026 5mo ago
Last Modified Jun 17, 2026 2w ago

Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on EX4k Series and QFX5k Series platforms allows an unauthenticated network-adjacent attacker flapping an interface to cause traffic between VXLAN Network Identifiers (VNIs) to drop, leading to a Denial of Service (DoS). On all EX4k and QFX5k platforms, a link flap in an EVPN-VXLAN configuration Link Aggregation Group (LAG) results in Inter-VNI traffic dropping when there are multiple load-balanced next-hop routes for the same destination. This issue is only applicable to systems that support EVPN-VXLAN Virtual Port-Link Aggregation Groups (VPLAG), such as the QFX5110, QFX5120, QFX5200, EX4100, EX4300, EX4400, and EX4650. Service can only be restored by restarting the affected FPC via the 'request chassis fpc restart slot <slot-number>' command. This issue affects Junos OS on EX4k and QFX5k Series:  * all versions before 21.4R3-S12,  * all versions of 22.2 * from 22.4 before 22.4R3-S8,  * from 23.2 before 23.2R2-S5,  * from 23.4 before 23.4R2-S5,  * from 24.2 before 24.2R2-S3, * from 24.4 before 24.4R2.

CVSS Details

Base Score
7.1
Exploitability
Impact
Vector string
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/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:Green
Attack Vector Adjacent
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
16.1% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-754

Affected Products 83

VendorProductVersionRange
juniperjunos* <21.4
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos21.4any
juniperjunos22.2any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos22.4any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.2any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos23.4any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.2any
juniperjunos24.4any
juniperjunos24.4any
juniperjunos24.4any
juniperjunos24.4any
juniperex4000*any
juniperex4100*any
juniperex4100-f*any
juniperex4100-h*any
juniperex4300*any
juniperex4400*any
juniperex4600*any
juniperex4650*any
juniperqfx5110*any
juniperqfx5120*any
juniperqfx5130*any
juniperqfx5200*any
juniperqfx5210*any
juniperqfx5220*any
juniperqfx5230-64cd*any
juniperqfx5240*any
juniperqfx5241*any
juniperqfx5700*any

References 2

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.