CVE-2026-21910Disclosure(juniper / ex4000)

LOWCVSS 7.1 · HIGH

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD 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.

0.5/ 10 priority

Sources & remediation

Weakness type (CWE)
CWE-754

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • ex4000
  • ex4100
  • ex4100-f
  • ex4100-h

Threat summary

  • 1 mentions across 1 observed day

What's happening

  • Technical details provided in 1 signal
  • Disclosure: 1 classified signal
  • 1 total mentions across 1 day

Affected systems

Vendors
Products
ex4000ex4100ex4100-fex4100-hex4300ex4400ex4600ex4650junosqfx5110

8 versions affected across 19 products

Deep dive

Activity timeline1 mentions / 1d
00111Mentions · 2026-07-13: 1Technical Details · 2026-07-13: 107-13
Signal classification1 categories
Disclosure
1100.0%
Referenced assets1 URL
Full discourse1 post
  • DailyCVE@dailycve
    Disclosure

    🟠 Juniper Junos #OS (EX4k/QFX5k), Improper Check for Unusual or Exceptional Conditions, #CVE‑2026‑21910 (Medium) -DC-Jul2026-914 https://dailycve.com/juniper-junos-os-ex4k-qfx5k-improper-check-for-unusual-or-exceptional-conditions-cve-2026-21910-medium-dc-jul2026-914/

    Post summary

    Juniper Junos OS (EX4k/QFX5k) faces a medium‑risk vulnerability (CVE‑2026‑21910) involving improper checks for unusual or exceptional conditions; no PoC, exploit, or patch information is disclosed.

    0000068
    218 followersView on X
CPE platform detail83 entries

83 of 83 entries

PartVendorProductVersionTarget SWTarget HW
HWjuniperex4000---
HWjuniperex4100---
HWjuniperex4100-f---
HWjuniperex4100-h---
HWjuniperex4300---
HWjuniperex4400---
HWjuniperex4600---
HWjuniperex4650---
OSjuniperjunos---
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos21.4--
OSjuniperjunos22.2--
OSjuniperjunos22.4--
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OSjuniperjunos22.4--
OSjuniperjunos22.4--
OSjuniperjunos22.4--
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OSjuniperjunos24.2--
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OSjuniperjunos24.2--
OSjuniperjunos24.4--
OSjuniperjunos24.4--
OSjuniperjunos24.4--
OSjuniperjunos24.4--
HWjuniperqfx5110---
HWjuniperqfx5120---
HWjuniperqfx5130---
HWjuniperqfx5200---
HWjuniperqfx5210---
HWjuniperqfx5220---
HWjuniperqfx5230-64cd---
HWjuniperqfx5240---
HWjuniperqfx5241---
HWjuniperqfx5700---

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