CVE-2024-39559: Juniper Junos OS Evolved

Medium severity, CVSS 5.9. EPSS: 0.4% chance of exploitation in the next 30 days.

An Improper Check for Unusual or Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS Evolved may allow a network-based unauthenticated attacker to crash the device (vmcore) by sending a specific TCP packet over an established TCP session with MD5 authentication enabled, destined to an accessible port on the device, resulting in a Denial of Service (DoS).  The receipt of this packet must occur within a specific timing window outside the attacker's control (i.e., race condition). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue only affects dual RE systems with Nonstop Active Routing (NSR) enabled. Exploitation can only occur over TCP sessions with MD5 authentication enabled (e.g., BGP with MD5 authentication). This issue affects Junos OS Evolved:  * All versions before 21.2R3-S8-EVO, * from 21.4-EVO before 21.4R3-S6-EVO, * from 22.1-EVO before 22.1R3-S4-EVO, * from 22.2-EVO before 22.2R3-S4-EVO, * from 22.3-EVO before 22.3R3-S3-EVO, * from 22.4-EVO before 22.4R2-S2-EVO, 22.4R3-EVO.

Affected products

• Juniper Junos OS Evolved: before 21.2 (fixed in 21.2); version 21.2 only; version 21.4 only; version 22.1 only; version 22.2 only; version 22.3 only; …

Published 2024-07-10. Last modified 2026-06-17.