Vulnerability Monitor

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CVE-2026-21905


A Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the SIP application layer gateway (ALG) of Juniper Networks Junos OS on SRX Series and MX Series with MX-SPC3 or MS-MPC allows an unauthenticated network-based attacker sending specific SIP messages over TCP to crash the flow management process, leading to a Denial of Service (DoS). On SRX Series, and MX Series with MX-SPC3 or MS-MPC service cards, receipt of multiple SIP messages causes the SIP headers to be parsed incorrectly, eventually causing a continuous loop and leading to a watchdog timer expiration, crashing the flowd process on SRX Series and MX Series with MX-SPC3, or mspmand process on MX Series with MS-MPC. This issue only occurs over TCP. SIP messages sent over UDP cannot trigger this issue. This issue affects Junos OS on SRX Series and MX Series with MX-SPC3 and MS-MPC: * all versions before 21.2R3-S10,  * from 21.4 before 21.4R3-S12,  * from 22.4 before 22.4R3-S8,  * from 23.2 before 23.2R2-S5,  * from 23.4 before 23.4R2-S6,  * from 24.2 before 24.2R2-S3,  * from 24.4 before 24.4R2-S1,  * from 25.2 before 25.2R1-S1, 25.2R2.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 28 products from juniper, from juniper, from juniper and 25 others, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2026-01-15T21:16:05.990

Last Modified

2026-01-23T19:40:26.687

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 7.5 (HIGH)

Weaknesses
  • Type: Primary
    CWE-835

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos < 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.2 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 21.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 22.4 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.2 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 23.4 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.2 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Hardware juniper mx10004 - No
Hardware juniper mx10008 - No
Hardware juniper mx2008 - No
Hardware juniper mx2010 - No
Hardware juniper mx2020 - No
Hardware juniper mx204 - No
Hardware juniper mx240 - No
Hardware juniper mx304 - No
Hardware juniper mx480 - No
Hardware juniper mx960 - No
Hardware juniper srx1500 - No
Hardware juniper srx1600 - No
Hardware juniper srx2300 - No
Hardware juniper srx300 - No
Hardware juniper srx320 - No
Hardware juniper srx340 - No
Hardware juniper srx345 - No
Hardware juniper srx380 - No
Hardware juniper srx4100 - No
Hardware juniper srx4120 - No
Hardware juniper srx4200 - No
Hardware juniper srx4300 - No
Hardware juniper srx4600 - No
Hardware juniper srx4700 - No
Hardware juniper srx5400 - No
Hardware juniper srx5600 - No
Hardware juniper srx5800 - No

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.