CVE-2024-21595Network attack vector

Unauthenticated device hang via ICMP-triggered PFE deadlock

Published Jan 12, 2024 · Updated Sep 3, 2024

Input validation failure in the PFE of Juniper Networks Junos OS allows remote attackers to hang affected EX and QFX devices. The PFE improperly validates the syntax of specific ICMP traffic; at sustained high rates, processing that traffic enters a deadlock. Exploitation requires network reachability and VXLAN configuration, and the resulting unresponsive device requires a manual restart.

CVSS severity7.5
High
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input validation failure in the PFE of Juniper Networks Junos OS allows remote attackers to hang affected EX and QFX devices. The PFE improperly validates the syntax of specific ICMP traffic; at sustained high rates, processing that traffic enters a deadlock. Exploitation requires network reachability and VXLAN configuration, and the resulting unresponsive device requires a manual restart.

The record

CVE
CVE-2024-21595
Published
Jan 12, 2024
Updated
Sep 3, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-1286, T1498.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=21.4R3 <21.4R3-S4
  2. Affected versionversion=22.1R3 <22.1R3-S3
  3. Affected versionversion=22.2R2 <22.2R3-S1
  4. Affected versionversion=22.3 <22.3R2-S2
  5. Affected versionversion=22.3 <22.3R2-S2, 22.3R3
  6. Affected versionversion=22.3 <22.3R3
  7. Affected versionversion=22.4 <22.4R2
  8. Affected versionversion=23.1 <23.1R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=21.4R3 <21.4R3-S4; version=22.1R3 <22.1R3-S3; version=22.2R2 <22.2R3-S1; version=22.3 <22.3R2-S2; version=22.3 <22.3R2-S2, 22.3R3; version=22.3 <22.3R3; version=22.4 <22.4R2; version=23.1 <23.1R2

Published CVSS scores

7.5Juniper Networks, Inc.CVSS:3.1/AV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1286Improper Validation of Syntactic Correctness of Input
T1498.001Network Denial of Service: Direct Network Flood

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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