CVE-2020-1638

Junos OS & Junos OS Evolved: A specific IPv4 packet can lead to FPC restart.

HIGH

7.5

CVSS Score

Published: April 8, 2020 at 07:26 PM UTC

Updated: June 17, 2026 at 03:02 AM UTC

12 products affected across 2 vendorsJunosJunos OS EvolvedMx960

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Severity

HIGH7.5

Exploit prediction

EPSS 1%

Description

The FPC (Flexible PIC Concentrator) of Juniper Networks Junos OS and Junos OS Evolved may restart after processing a specific IPv4 packet. Only packets destined to the device itself, successfully reaching the RE through existing edge and control plane filtering, will be able to cause the FPC restart. When this issue occurs, all traffic via the FPC will be dropped. By continuously sending this specific IPv4 packet, an attacker can repeatedly crash the FPC, causing an extended Denial of Service (DoS) condition. This issue can only occur when processing a specific IPv4 packet. IPv6 packets cannot trigger this issue. This issue affects: Juniper Networks Junos OS on MX Series with MPC10E or MPC11E and PTX10001: 19.2 versions prior to 19.2R1-S4, 19.2R2; 19.3 versions prior to 19.3R2-S2, 19.3R3; 19.4 versions prior to 19.4R1-S1, 19.4R2. Juniper Networks Junos OS Evolved on on QFX5220, and PTX10003 series: 19.2-EVO versions; 19.3-EVO versions; 19.4-EVO versions prior to 19.4R2-EVO. This issue does not affect Junos OS versions prior to 19.2R1. This issue does not affect Junos OS Evolved versions prior to 19.2R1-EVO.

Affected

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

Junos OS Evolved · Juniper

95%

19.2 r1 19.3 r2 19.4 r1

juniper-ptx10003 (environment) · juniper-qfx5220 (environment)

Junos · Juniper Networks

95%

19.2 ≤ v < 19.2R1-S4, 19.2R219.3 ≤ v < 19.3R2-S2, 19.3R319.4 ≤ v < 19.4R1-S1, 19.4R219.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.4 19.4 r1

Vendor states this is fixed in 19.2R1 (unaffected)

Affected range stops below 19.2R1-S4, 19.2R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R2-S2, 19.3R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R1-S1, 19.4R2, so it looks safe — our inference, not a vendor statement

juniper-mx10003 (environment) · juniper-mx2008 (environment) · juniper-mx2010 (environment) · juniper-mx2020 (environment) · juniper-mx240 (environment) · juniper-mx480 (environment) · juniper-mx960 (environment)

Junos OS Evolved · Juniper Networks

60%

19.4-EVO ≤ v < 19.4R2-EVO19.2-EVO 19.3-EVO 19.2-EVO 19.4-EVO

Vendor states this is fixed in 19.2R1-EVO (unaffected)

Affected range stops below 19.4R2-EVO, so it looks safe — our inference, not a vendor statement

Mx10003 · Juniperdevice

80%

All versions

Mx2008 · Juniperdevice

80%

All versions

Mx2010 · Juniperdevice