Juniper Junos OS up to 23.4R1 on MX Packet Forwarding Engine unusual condition

Summaryinfo

A vulnerability, which was classified as critical, has been found in Juniper Junos OS up to 23.4R1 on MX. The affected element is an unknown function of the component Packet Forwarding Engine. The manipulation leads to unusual condition. This vulnerability is uniquely identified as CVE-2025-30660. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Juniper Junos OS up to 23.4R1 on MX and classified as critical. This issue affects an unknown functionality of the component Packet Forwarding Engine. The manipulation with an unknown input leads to a unusual condition vulnerability. Using CWE to declare the problem leads to CWE-754. The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product. 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 allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).When processing a high rate of specific GRE traffic destined to the device, the respective PFE will hang causing traffic forwarding to stop. When this issue occurs the following logs can be observed: <fpc #> MQSS(0): LI-3: Received a parcel with more than 512B accompanying data CHASSISD_FPC_ASIC_ERROR: ASIC Error detected <...> This issue affects Junos OS: * all versions before 21.2R3-S9, * 21.4 versions before 21.4R3-S8, * 22.2 versions before 22.2R3-S4, * 22.4 versions before 22.4R3-S5, * 23.2 versions before 23.2R2-S2, * 23.4 versions before 23.4R2.

The advisory is shared at supportportal.juniper.net. The identification of this vulnerability is CVE-2025-30660 since 03/24/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 01/24/2026).

The vulnerability scanner Nessus provides a plugin with the ID 234093 (Juniper Junos OS Vulnerability (JSA96471)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 21.2R3-S9, 21.4R3-S8, 22.2R3-S4, 22.4R3-S5, 23.2R2-S2 or 23.4R2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (234093). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Router Operating System

Vendor

• Juniper

Name

• Junos OS

Version

• 21.2R3-S8
• 21.4R3-S7
• 22.2R3-S3
• 22.4R3-S4
• 23.2R2-S1
• 23.4R1

License

• commercial

Website

• Vendor: https://www.juniper.net/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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