Juniper Networks Junos OS up to 23.2R2-S3/23.4R2-S4/24.2R1 Packet Forwarding Engine resource consumption

Summaryinfo

A vulnerability identified as critical has been detected in Juniper Networks Junos OS up to 23.2R2-S3/23.4R2-S4/24.2R1. This affects an unknown part of the component Packet Forwarding Engine. The manipulation leads to resource consumption. This vulnerability is documented as CVE-2026-102077. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Juniper Networks Junos OS up to 23.2R2-S3/23.4R2-S4/24.2R1. It has been rated as critical. This issue affects some unknown functionality of the component Packet Forwarding Engine. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. The summary by CVE is:

An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series with SPC3 allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On MX Series with SPC3 line-card and source NAT configuration, when a specific malformed IPv6 packet is received, it is not dropped but instead a session is created and NAT resources are allocated. Continued receipt of such packets will eventually lead to session or resource exhaustion, which will impact all traffic through the device. To recover the device needs to be rebooted. To monitor session usage, use the following: show services sessions summary To monitor source NAT resource usage, use the following:  show services nat pool This issue affects Junos OS on MX Series with SPC3: * All versions before 23.2R2-S4; * 23.4 versions before 23.4R2-S5; * 24.2 versions before 24.2R2.

It is possible to read the advisory at supportportal.juniper.net. The identification of this vulnerability is CVE-2026-102077 since 09/28/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/14/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 23.2R2-S4, 23.4R2-S5 or 24.2R2 eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Juniper Networks

Name

• Junos OS

Version

• 23.2R2-S3
• 23.4R2-S4
• 24.2R1

License

• commercial

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CPE 2.2info

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