An Improper Handling of Exceptional Conditions vulnerability in the Routing Protocol Daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved allows an attacker sending a specific malformed BGP update message to cause the session to reset, resulting in a Denial of Service (DoS). Continued receipt and processing of these malformed BGP update messages will create a sustained Denial of Service (DoS) condition.

Upon receipt of a BGP update message over an established BGP session containing a specifically malformed tunnel encapsulation attribute, when segment routing is enabled, internal processing of the malformed attributes within the update results in improper parsing of remaining attributes, leading to session reset:

BGP SEND Notification code 3 (Update Message Error) subcode 1 (invalid attribute list)

Only systems with segment routing enabled are vulnerable to this issue.

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

This issue affects:

Junos OS:

• All versions before 21.4R3-S8,
• from 22.2 before 22.2R3-S4,
• from 22.3 before 22.3R3-S3,
• from 22.4 before 22.4R3-S3,
• from 23.2 before 23.2R2-S1,
• from 23.4 before 23.4R1-S2, 23.4R2.

Junos OS Evolved: 

• All versions before 21.4R3-S8-EVO,
• from 22.2-EVO before 22.2R3-S4-EVO,
• from 22.3-EVO before 22.3R3-S3-EVO,
• from 22.4-EVO before 22.4R3-S3-EVO,
• from 23.2-EVO before 23.2R2-S1-EVO,
• from 23.4-EVO before 23.4R1-S2-EVO, 23.4R2-EVO.