CVE-2024-21599

MPC restart via PTP-triggered PFE memory leak

Published Jan 12, 2024 · Updated Jun 16, 2025

Memory leak in the PFE of Juniper Networks Junos OS on MX Series allows adjacent unauthenticated attackers to crash and restart an MPC. The PFE fails to release memory when an unsupported MPC3E receives PTP packets, increasing LAN-buffer use until the MPC crashes and restarts. Exposure requires an MX Series device with MPC3E and a release before 20.4R3-S3; 21.1 before 21.1R3-S4; 21.2 before 21.2R3; affected 21.3 releases; 21.4 before 21.4R2; or 22.1 before 22.1R2.

CVSS severity6.5
Medium
EPSS probability0.29%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in the PFE of Juniper Networks Junos OS on MX Series allows adjacent unauthenticated attackers to crash and restart an MPC. The PFE fails to release memory when an unsupported MPC3E receives PTP packets, increasing LAN-buffer use until the MPC crashes and restarts. Exposure requires an MX Series device with MPC3E and a release before 20.4R3-S3; 21.1 before 21.1R3-S4; 21.2 before 21.2R3; affected 21.3 releases; 21.4 before 21.4R2; or 22.1 before 22.1R2.

The record

CVE
CVE-2024-21599
Published
Jan 12, 2024
Updated
Jun 16, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-401, T1499.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 16, 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-S3
  2. Affected versionversion=21.1 <21.1R3-S4
  3. Affected versionversion=21.2 <21.2R3
  4. Affected versionversion=21.3 <21.3R2-S1, 21.3R3
  5. Affected versionversion=21.4 <21.4R2
  6. Affected versionversion=22.1 <22.1R2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

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

Published CVSS scores

6.5Juniper Networks, Inc.CVSS: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 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.002Endpoint Denial of Service: Service Exhaustion

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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