CVE-2024-39542

Junos OS and Junos OS Evolved: A malformed CFM packet or specific transit traffic leads to FPC crash

HIGH

7.5

CVSS Score

Published: July 11, 2024 at 04:17 PM UTC

Updated: June 17, 2026 at 07:42 AM UTC

3 products affected across 2 vendorsJunosJunos OS EvolvedJunos OS Evolved

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Severity

HIGH7.5

Exploit prediction

EPSS 0.5%

SSVC

No known exploit

Description

An Improper Validation of Syntactic Correctness of Input vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series with MPC10/11 or LC9600, MX304, and Junos OS Evolved on ACX Series and PTX Series allows an unauthenticated, network based attacker to cause a Denial-of-Service (DoS). This issue can occur in two scenarios: 1. If a device, which is configured with SFLOW and ECMP, receives specific valid transit traffic, which is subject to sampling, the packetio process crashes, which in turn leads to an evo-aftman crash and causes the FPC to stop working until it is restarted. (This scenario is only applicable to PTX but not to ACX or MX.) 2. If a device receives a malformed CFM packet on an interface configured with CFM, the packetio process crashes, which in turn leads to an evo-aftman crash and causes the FPC to stop working until it is restarted. Please note that the CVSS score is for the formally more severe issue 1. The CVSS score for scenario 2. is: 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) This issue affects Junos OS: * All versions before 21.2R3-S4, * 21.4 versions before 21.4R2, * 22.2 versions before 22.2R3-S2; Junos OS Evolved: * All versions before 21.2R3-S8-EVO, * 21.4 versions before 21.4R2-EVO.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos OS Evolved · Juniper

95%

v < 21.2r3-s8-evo21.4 ≤ v < 21.4r2-evo21.2 21.2 r1 21.2 r1-s1 21.2 r1-s2 21.2 r2 21.2 r2-s1 21.2 r2-s2 21.2 r3 21.2 r3-s1 21.2 r3-s2 21.2 r3-s3 21.2 r3-s4 21.2 r3-s5 21.2 r3-s6 21.2 r3-s7 21.4 21.4 r1 21.4 r1-s1 21.4 r1-s2

Affected range stops below 21.2r3-s8-evo, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.4r2-evo, so it looks safe — our inference, not a vendor statement

Junos · Juniper Networks

95%

v < 21.2R3-S421.4 ≤ v < 21.4R222.2 ≤ v < 22.2R2-S1, 22.2R322.2 ≤ v < 22.2r2-s122.2 ≤ v < 22.2r321.4 21.4 r1 21.4 r1-s1 21.4 r1-s2 22.2 22.2 r1 22.2 r1-s1 22.2 r1-s2 22.2 r2

Affected range stops below 21.2R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.4R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2R2-S1, 22.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2r2-s1, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2r3, so it looks safe — our inference, not a vendor statement

Junos OS Evolved · Juniper Networks

60%

v < 21.2R3-S8-EVO21.4 ≤ v < 21.4R2-EVO21.4

Affected range stops below 21.2R3-S8-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.4R2-EVO, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://supportportal.juniper.net/JSA83002

References (1)

Vendor Advisory

Source: [email protected]

https://supportportal.juniper.net/JSA83002

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHjuniper

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-1286

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