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2021-01 Security Bulletin: Junos OS and Junos OS Evolved: In bidirectional LSP configurations, on MPLS egress router RPD may core upon receipt of specific malformed RSVP packet. (CVE-2021-0208)



Article ID: JSA11098 SECURITY_ADVISORIES Last Updated: 13 Jan 2021Version: 4.0
Product Affected:
This issue affects Junos OS 15.1X49, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1. This issue affects Junos OS Evolved 19.3, 19.4, 20.1.

An improper input validation vulnerability in the Routing Protocol Daemon (RPD) service of Juniper Networks Junos OS allows an attacker to send a malformed RSVP packet when bidirectional LSPs are in use, which when received by an egress router crashes the RPD causing a Denial of Service (DoS) condition. Continued receipt of the packet will sustain the Denial of Service.

This issue affects:

Juniper Networks Junos OS:

  • All versions prior to 17.3R3-S10 except 15.1X49-D240 for SRX series;
  • 17.4 versions prior to 17.4R3-S2;
  • 18.1 versions prior to 18.1R3-S10;
  • 18.2 versions prior to 18.2R2-S7, 18.2R3-S4;
  • 18.3 versions prior to 18.3R3-S2;
  • 18.4 versions prior to 18.4R1-S8, 18.4R2-S6, 18.4R3-S2;
  • 19.1 versions prior to 19.1R1-S5, 19.1R3-S3;
  • 19.2 versions prior to 19.2R3;
  • 19.3 versions prior to 19.3R2-S5, 19.3R3;
  • 19.4 versions prior to 19.4R2-S2, 19.4R3-S1;
  • 20.1 versions prior to 20.1R1-S4, 20.1R2;
  • 15.1X49 versions prior to 15.1X49-D240 on SRX Series.

Juniper Networks Junos OS Evolved:

  • 19.3 versions prior to 19.3R2-S5-EVO;
  • 19.4 versions prior to 19.4R2-S2-EVO;
  • 20.1 versions prior to 20.1R1-S4-EVO.

The following are examples of minimal configurations:

[protocols mpls label-switched-path <lsp-name> corouted-bidirectional;]


[logical-systems <logical-system-name> protocols mpls label-switched-path <lsp-name> corouted-bidirectional;]

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-2021-0208.


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

Junos OS: 15.1X49-D240, 17.3R3-S10, 17.4R3-S2, 18.1R3-S10, 18.2R2-S7, 18.2R3-S4, 18.3R3-S2, 18.4R1-S8, 18.4R2-S6, 18.4R3-S2, 19.1R1-S5, 19.1R3-S3, 19.2R3, 19.3R2-S5, 19.3R3, 19.4R2-S2, 19.4R3-S1, 20.1R1-S4, 20.1R2, 20.2R1, and all subsequent releases.

Note: With the exception of SRX Series products using version 15.1X49-D240, all products using Junos OS prior to 17.3R3-S10 are affected and will not be fixed by Juniper Networks, Inc.

Junos OS Evolved: 19.3R2-S5-EVO, 19.4R2-S2-EVO, 20.1R1-S4-EVO, and all subsequent releases.

This issue is being tracked as 1493718.


If bidirectional LSPs are running in the network, when changing family mpls maximum-labels on an interface, first disable RSVP for this interface.

You can include the disable statement at the following hierarchy levels:

[edit protocols rsvp interface interface-name ]
[edit logical-systems logical-system-name protocols rsvp interface interface-name ]

See the MPLS RSVP disable configuration guide for further details.

Software releases or updates are available for download at
Modification History:
2021-01-13: Initial Publication.
CVSS Score:
8.8 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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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