CVE-2024-21585: Junos OS and Junos OS Evolved: BGP session flaps on NSR-enabled devices can cause rpd crash
An Improper Handling of Exceptional Conditions vulnerability in BGP session processing of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker, using specific timing outside the attacker's control, to flap BGP sessions and cause the routing protocol daemon (rpd) process to crash and restart, leading to a Denial of Service (DoS) condition. Continued BGP session flapping will create a sustained Denial of Service (DoS) condition.
This issue only affects routers configured with non-stop routing (NSR) enabled. Graceful Restart (GR) helper mode, enabled by default, is also required for this issue to be exploitable.
Note: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability. When the BGP session flaps on the NSR-enabled router, the device enters GR-helper/LLGR-helper mode due to the peer having negotiated GR/LLGR-restarter capability and the backup BGP requests for replication of the GR/LLGR-helper session, master BGP schedules, and initiates replication of GR/LLGR stale routes to the backup BGP. In this state, if the BGP session with the BGP peer comes up again, unsolicited replication is initiated for the peer without cleaning up the ongoing GR/LLGR-helper mode replication. This parallel two instances of replication for the same peer leads to the assert if the BGP session flaps again.
This issue affects:
Juniper Networks Junos OS
All versions earlier than 20.4R3-S9; 21.2 versions earlier than 21.2R3-S7; 21.3 versions earlier than 21.3R3-S5; 21.4 versions earlier than 21.4R3-S5; 22.1 versions earlier than 22.1R3-S4; 22.2 versions earlier than 22.2R3-S3; 22.3 versions earlier than 22.3R3-S1; 22.4 versions earlier than 22.4R2-S2, 22.4R3; 23.2 versions earlier than 23.2R1-S1, 23.2R2.
Juniper Networks Junos OS Evolved
All versions earlier than 21.3R3-S5-EVO; 21.4 versions earlier than 21.4R3-S5-EVO; 22.1 versions earlier than 22.1R3-S4-EVO; 22.2 versions earlier than 22.2R3-S3-EVO; 22.3 versions earlier than 22.3R3-S1-EVO; 22.4 versions earlier than 22.4R2-S2-EVO, 22.4R3-EVO; 23.2 versions earlier than 23.2R1-S1-EVO, 23.2R2-EVO.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 21.2R3-S7 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 21.3R3-S5 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 21.4R3-S5 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 21.4R3-S5-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.1R3-S4 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.1R3-S4-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.2R3-S3 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.2R3-S3-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.3R3-S1 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.3R3-S1-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.4R2-S2 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.4R3 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.4R2-S2-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 22.4R3-EVO - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 23.2R1-S1 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 23.2R2 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 20.4R3-S9 - Upgrade
Upgrade
Juniper Networks Junos OS and Junos OS Evolvedto a version that resolves this vulnerability.Fixed in 21.3R3-S5-EVO - Compensating control
Ensure Graceful Restart (GR) helper mode is not left enabled by default on affected Junos OS/JunOS OS Evolved NSR-enabled devices, since GR helper mode (enabled by default) is required for this issue to be exploitable.
Event History
Frequently Asked Questions
What is the severity of CVE-2024-21585?
CVE-2024-21585 is classified as a high severity vulnerability due to its potential to cause significant disruption of BGP sessions.
How do I fix CVE-2024-21585?
To mitigate CVE-2024-21585, update your Junos OS or Junos OS Evolved to the latest patched version available from Juniper Networks.
Who is affected by CVE-2024-21585?
CVE-2024-21585 affects various versions of Juniper Networks Junos OS and Junos OS Evolved, specifically versions 20.4 and 21.2 through 22.4.
What kind of attacks can CVE-2024-21585 be exploited for?
This vulnerability can be exploited by an unauthenticated remote attacker to manipulate BGP session states, potentially disrupting network routing.
Is there a workaround for CVE-2024-21585?
While a patch is the most effective solution for CVE-2024-21585, network administrators are advised to monitor BGP session logs for unusual patterns of activity as a temporary measure.