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2020-04 Security Bulletin: Junos OS & Junos OS Evolved: A specific IPv4 packet can lead to FPC restart. (CVE-2020-1638)



Article ID: JSA11019 SECURITY_ADVISORIES Last Updated: 08 Apr 2020Version: 1.0
Product Affected:
This issue affects Junos OS 19.2, 19.3, 19.4, affected platforms: MX Series with MPC10E or MPC11E and PTX10001. This issue affects Junos OS Evolved 19.2-EVO, 19.3-EVO, 19.4-EVO, affected platforms: QFX5220, and PTX10003 series.

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.
Junos OS Evolved versions prior to 19.2R1-EVO.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2020-1638.


The following software releases have been updated to resolve this specific issue:

Junos OS: 19.2R1-S4, 19.2R2, 19.3R2-S2, 19.3R3, 19.4R1-S1, 19.4R2, 20.1R1, and all subsequent releases.

Junos OS Evolved: 19.4R2-EVO, 20.1R1-EVO, and all subsequent releases.

This issue is being tracked as 1493176.


There is no workaround for this issue.

Standard security best common practices such as limiting packet toward the RE only from trusted networks/host using firewall filter in combination with source address anti-spoofing should be applied to reduce the risk of exposure.

Software Releases, patches and updates are available at
Modification History:
‚Äč2020-04-08: Initial publication
CVSS Score:
7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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