CVE-2024-39542Network attack vector

FPC outage via malformed or sampled traffic

Published Jul 11, 2024 · Updated Aug 2, 2024

Input validation flaws in Junos OS and Junos OS Evolved allow remote attackers to stop an FPC with crafted network traffic. The Packet Forwarding Engine's packetio process mishandles either sampled transit traffic or a malformed CFM packet, crashes evo-aftman, and leaves the FPC inoperative. Reachability requires SFLOW with ECMP on PTX for the transit-traffic path, or CFM on the receiving interface; service remains interrupted until the FPC is restarted.

CVSS severity8.7
High
EPSS probability0.47%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input validation flaws in Junos OS and Junos OS Evolved allow remote attackers to stop an FPC with crafted network traffic. The Packet Forwarding Engine's packetio process mishandles either sampled transit traffic or a malformed CFM packet, crashes evo-aftman, and leaves the FPC inoperative. Reachability requires SFLOW with ECMP on PTX for the transit-traffic path, or CFM on the receiving interface; service remains interrupted until the FPC is restarted.

The record

CVE
CVE-2024-39542
Published
Jul 11, 2024
Updated
Aug 2, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-1286, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 11, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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=0 <21.2r3-s8-evo
  2. Affected versionversion=0 <21.2R3-S8-EVO
  3. Affected versionversion=21.4 <21.4r2-evo
  4. Affected versionversion=21.4 <21.4R2-EVO

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=0 <21.2r3-s8-evo; version=0 <21.2R3-S8-EVO; version=21.4 <21.4r2-evo; version=21.4 <21.4R2-EVO
Juniper Networks · Junos OSversion=0 <21.2r3-s4; version=0 <21.2R3-S4; version=21.4 <21.4r2; version=21.4 <21.4R2; version=22.2 <22.2r2-s1; version=22.2 <22.2R2-S1, 22.2R3; version=22.2 <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
7.5Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Juniper NetworksCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1286Improper Validation of Syntactic Correctness of Input
T1499Endpoint Denial of Service

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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