CVE-2024-39531: Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-07-11 · updated 2026-06-17
Weakness: CWE-229

Description

An Improper Handling of Values vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS Evolved on ACX 7000 Series allows a network-based, unauthenticated attacker to cause a Denial-of-Service (DoS). If a value is configured for DDoS bandwidth or burst parameters for any protocol in a queue, all protocols which share the same queue will have their bandwidth or burst value changed to the new value. If, for example, OSPF was configured with a certain bandwidth value, ISIS would also be limited to this value. So inadvertently either the control plane is open for a high level of specific traffic which was supposed to be limited to a lower value, or the limit for a certain protocol is so low that chances to succeed with a volumetric DoS attack are significantly increased. This issue affects Junos OS Evolved on ACX 7000 Series: * All versions before 21.4R3-S7-EVO, * 22.1 versions before 22.1R3-S6-EVO, * 22.2 versions before 22.2R3-S3-EVO, * 22.3 versions before 22.3R3-S3-EVO, * 22.4 versions before 22.4R3-S2-EVO, * 23.2 versions before 23.2R2-EVO, * 23.4 versions before 23.4R1-S1-EVO, 23.4R2-EVO.

Affected products

Juniper Networks Junos OS Evolved: before 21.4; 21.4, 21.4-r1, 21.4-r1-s1, 21.4-r1-s2, 21.4-r2, 21.4-r2-s1 (+56) — fixed in 21.4

How to fix

Upgrade to a fixed version: Juniper Networks Junos OS Evolved 21.4. Check the vendor advisory for mitigations.

References

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