CVE-2023-44203

Service interruption via cross-VLAN IGMP packet flooding

Published Oct 12, 2023 · Updated Sep 17, 2024

Improper exception handling in the Junos OS Packet Forwarding Engine allows adjacent attackers to cause packet flooding with crafted IGMP traffic. A specific IGMP packet received in an isolated VLAN is incorrectly duplicated to every port under the primary VLAN instead of remaining isolated. Exploitation requires adjacent-network access and an isolated private VLAN on an affected switch, and the resulting flood interrupts packet-forwarding availability.

CVSS severity6.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in the Junos OS Packet Forwarding Engine allows adjacent attackers to cause packet flooding with crafted IGMP traffic. A specific IGMP packet received in an isolated VLAN is incorrectly duplicated to every port under the primary VLAN instead of remaining isolated. Exploitation requires adjacent-network access and an isolated private VLAN on an affected switch, and the resulting flood interrupts packet-forwarding availability.

The record

CVE
CVE-2023-44203
Published
Oct 12, 2023
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-703, T1498
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <20.4R3-S5
  2. Affected versionversion=21.1 <21.1R3-S4
  3. Affected versionversion=21.2 <21.2R3-S3
  4. Affected versionversion=21.3 <21.3R3-S5
  5. Affected versionversion=21.4 <21.4R3-S2
  6. Affected versionversion=22.1 <22.1R3
  7. Affected versionversion=22.2 <22.2R3
  8. Affected versionversion=22.3 <22.3R2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S5; version=21.1 <21.1R3-S4; version=21.2 <21.2R3-S3; version=21.3 <21.3R3-S5; version=21.4 <21.4R3-S2; version=22.1 <22.1R3; version=22.2 <22.2R3; version=22.3 <22.3R2

Published CVSS scores

6.5Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-703Improper Check or Handling of Exceptional Conditions
T1498Network Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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