Product Affected

This issue affects Junos OS: All versions before 20.4R3-S10, from 21.1R1*, 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, 22.4, 23.2. This issue affects Junos OS Evolved: 21.2-EVO, 21.3-EVO, 21.4-EVO, 22.1-EVO, 22.2-EVO, 22.3-EVO, 22.4-EVO, 23.2-EVO.
High
7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem

An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS).

When certain specific crafted BGP UPDATE messages are received over an established BGP session, one BGP session may be torn down with an UPDATE message error, or the issue may propagate beyond the local system which will remain non-impacted, but may affect one or more remote systems. This issue is exploitable remotely as the crafted UPDATE message can propagate through unaffected systems and intermediate BGP speakers.
Continuous receipt of the crafted BGP UPDATE messages will create a sustained Denial of Service (DoS) condition for impacted devices.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations.  This issue requires a remote attacker to have at least one established BGP session.

This issue affects 

Junos OS: 

  • All versions before 20.4R3-S10,
  • from 21.1 through 21.1R1*,
  • from 21.2 before 21.2R3-S5,
  • from 21.3 before 21.3R3-S5,
  • from 21.4 before 21.4R3-S5 (unaffected from 21.4R3-S5, affected from 21.4R3-S6, unaffected from 21.4R3-S7),
  • from 22.1 before 22.1R3-S4,
  • from 22.2 before 22.2R3-S3,
  • from 22.3 before 22.3R3-S1,
  • from 22.4 before 22.4R3,
  • from 23.2 before 23.2R2.
Junos OS Evolved:
  • All versions before 20.4R3-S10-EVO,
  • from 21.2-EVO before 21.2R3-S7-EVO,
  • from 21.3-EVO before 21.3R3-S5-EVO,
  • from 21.4-EVO before 21.4R3-S5-EVO,
  • from 22.1-EVO before 22.1R3-S4-EVO,
  • from 22.2-EVO before 22.2R3-S3-EVO,
  • from 22.3-EVO before 22.3R3-S1-EVO,
  • from 22.4-EVO before 22.4R3-EVO,
  • from 23.2-EVO before 23.2R2-EVO.

Solution

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

Junos OS: 20.4R3-S10, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5 or 21.4R3-S7, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R3, 23.2R2, 23.3R2, 23.4R1, and all subsequent releases

Note: except for Junos OS 21.4R3-S6 which is affected and unfixed.

Junos OS Evolved: 20.4R3-S10-EVO, 21.2R3-S7-EVO, 21.3R3-S5-EVO, 21.4R3-S5-EVO, 22.1R3-S4-EVO, 22.2R3-S3-EVO, 22.3R3-S1-EVO, 22.4R3-EVO, 23.2R2-EVO, 23.4R1-EVO, and all subsequent releases.

It is important that customers implement the workaround in addition to taking any updated software as these crafted UPDATE messages may be propagated to other devices even if non-impacted locally, thereby protecting the network by stopping the propagation of these crafted UPDATE messages.
The workaround is to configure BGP error tolerance by way of:

  [ protocols bgp bgp-error-tolerance ... ]

Additional details can be found at https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h...

Juniper considers configuring this option to be a Best Common Practice (BCP) as it not only prevents this issue from happening, but protects against similar issues as well.

This issue is being tracked as PR 1709837 which is visible on the Customer Support website.

Note: Juniper SIRT's policy [juniper.net] is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).

Workaround

The workaround is to configure BGP error tolerance by way of:

  [ protocols bgp bgp-error-tolerance ... ]

Additional details can be found at https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h...

Juniper considers configuring this option to be a Best Common Practice (BCP) as it not only prevents this issue from happening, but protects against similar issues as well.

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net] "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History

2023-08-29: Initial Publication
2024-09-11: Updated affected and resolved in releases for Junos OS and Junos OS Evolved.

Related Information

Acknowledgements

The Juniper SIRT would like to acknowledge and thank Ben Cartwright-Cox / bgp.tools, Finder, for responsibly reporting this vulnerability.