CVE-2026-102077

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Denial-of-Service in Juniper Junos OS on MX Series with SPC3

Publication date: 2026-10-14

Last updated on: 2026-10-14

Assigner: Juniper Networks, Inc.

Description

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.

CVSS Scores

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Meta Information

Published

2026-10-14

Last Modified

2026-10-14

Generated

2026-10-19

AI Q&A

2026-10-15

EPSS Evaluated

2026-10-18

NVD

CVE-2026-102077

EUVD

EUVD-2026-101410

Affected Vendors & Products

Vendor	Product	Version / Range
Juniper	Networks	Junos OS 0
Juniper	Networks	Junos OS 23.4
Juniper	Networks	Junos OS 24.2

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
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.

Attack-Flow Graph

Executive Summary

This is an Improper Check for Unusual or Exceptional Conditions vulnerability in Juniper Networks Junos OS on MX Series with SPC3. When a malformed IPv6 packet is received, the device incorrectly creates a session and allocates NAT resources instead of dropping the packet. Continued receipt of such packets leads to resource exhaustion, causing a Denial-of-Service (DoS) that impacts all traffic. The device must be rebooted to recover.

Detection Guidance

To detect this vulnerability, monitor session and NAT resource usage on affected Juniper MX Series devices with SPC3. Use the commands: show services sessions summary to check session usage and show services nat pool to monitor NAT resource allocation.

If abnormal resource consumption is observed, it may indicate exploitation of this vulnerability.

Impact Analysis

This vulnerability allows an unauthenticated attacker to disrupt network traffic by causing a DoS. Affected devices may become unresponsive, leading to loss of connectivity and service interruptions for all users. Monitoring session and NAT resource usage is recommended to detect exploitation attempts.

Compliance Impact

This vulnerability can impact compliance with GDPR and HIPAA by causing a Denial-of-Service (DoS) condition, leading to potential disruptions in data processing and availability. For GDPR, this may affect the integrity and availability of personal data processing systems, while for HIPAA, it could disrupt critical healthcare services or data access.

Mitigation Strategies

Upgrade Junos OS on affected MX Series devices with SPC3 to a fixed version: 23.2R2-S4 or later, 23.4R2-S5 or later, or 24.2R2 or later. If immediate upgrade is not possible, consider disabling source NAT or applying rate limiting to IPv6 traffic as temporary mitigations.

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