CVE-2024-21585

Junos OS and Junos OS Evolved: BGP session flaps on NSR-enabled devices can cause rpd crash

State: Published
Severity: 5.9 Medium
Published: Jan 12, 2024
Updated: Nov 14, 2024
Reserved: Dec 27, 2023

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.9 Medium	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	juniper

Weaknesses

CWE-755 Improper Handling of Exceptional Conditions

Affected Products

Product	Versions
Junos OSJuniper Networks	before 20.4R3-S9Affected 21.2 to before 21.2R3-S7Affected 21.3 to before 21.3R3-S5Affected 21.4 to before 21.4R3-S5Affected 22.1 to before 22.1R3-S4Affected 22.2 to before 22.2R3-S3Affected 22.3 to before 22.3R3-S1Affected 22.4 to before 22.4R2-S2, 22.4R3Affected 23.2 to before 23.2R1-S1, 23.2R2Affected
Junos OS EvolvedJuniper Networks	before 21.3R3-S5-EVOAffected 21.4 to before 21.4R3-S5-EVOAffected 22.1 to before 22.1R3-S4-EVOAffected 22.2 to before 22.2R3-S3-EVOAffected 22.3 to before 22.3R3-S1-EVOAffected 22.4 to before 22.4R2-S2-EVO, 22.4R3-EVOAffected 23.2 to before 23.2R1-S1-EVO, 23.2R2-EVOAffected

References

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