CVE-2024-21600

FPC hang via down-tunnel MPLS reject path

Published Jan 12, 2024 · Updated Jun 17, 2025

Denial of service in Juniper Networks Junos OS PTX Series allows adjacent unauthenticated attackers to hang an FPC with MPLS traffic. When an FTI tunnel is down, MPLS packets hit the reject next hop and are redirected to the CPU, wedging the host path. The issue is limited to specified PTX models and line cards; successful exploitation hangs the FPC until an operator manually restarts it.

CVSS severity6.5
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Juniper Networks Junos OS PTX Series allows adjacent unauthenticated attackers to hang an FPC with MPLS traffic. When an FTI tunnel is down, MPLS packets hit the reject next hop and are redirected to the CPU, wedging the host path. The issue is limited to specified PTX models and line cards; successful exploitation hangs the FPC until an operator manually restarts it.

The record

CVE
CVE-2024-21600
Published
Jan 12, 2024
Updated
Jun 17, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-76, T1498
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2025Record 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-S8
  2. Affected versionversion=21.1 <21.1R3-S4
  3. Affected versionversion=21.2 <21.2R3-S6
  4. Affected versionversion=21.3 <21.3R3-S3
  5. Affected versionversion=21.4 <21.4R3-S5
  6. Affected versionversion=22.1 <22.1R2-S2, 22.1R3
  7. Affected versionversion=22.2 <22.2R2-S1, 22.2R3

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S8; version=21.1 <21.1R3-S4; version=21.2 <21.2R3-S6; version=21.3 <21.3R3-S3; version=21.4 <21.4R3-S5; version=22.1 <22.1R2-S2, 22.1R3; version=22.2 <22.2R2-S1, 22.2R3

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.

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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-76Improper Neutralization of Equivalent Special Elements
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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