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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)

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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.
Problem:

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;]

or

[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.

Solution:

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.

Workaround:

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.

Implementation:
Software releases or updates are available for download at https://www.juniper.net/support/downloads/.
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:
High
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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