CVE-2026-21905
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2026-01-15

Last updated on: 2026-01-15

Assigner: Juniper Networks, Inc.

Description
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,Β  * from 21.4 before 21.4R3-S12,Β  * from 22.4 before 22.4R3-S8,Β  * from 23.2 before 23.2R2-S5,Β  * from 23.4 before 23.4R2-S6,Β  * from 24.2 before 24.2R2-S3,Β  * from 24.4 before 24.4R2-S1,Β  * from 25.2 before 25.2R1-S1, 25.2R2.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2026-01-15
Last Modified
2026-01-15
Generated
2026-05-07
AI Q&A
2026-01-16
EPSS Evaluated
2026-05-05
NVD
EUVD
Affected Vendors & Products
Showing 9 associated CPEs
Vendor Product Version / Range
juniper junoss to 21.2r3-s10 (exc)
juniper junoss to 21.4r3-s12 (exc)
juniper junoss to 22.4r3-s8 (exc)
juniper junoss to 23.2r2-s5 (exc)
juniper junoss to 23.4r2-s6 (exc)
juniper junoss to 24.2r2-s3 (exc)
juniper junoss to 24.4r2-s1 (exc)
juniper junoss to 25.2r1-s1 (exc)
juniper junoss 25.2r2
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-835 The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is an infinite loop issue in the SIP application layer gateway (ALG) of Juniper Networks Junos OS on certain SRX and MX Series devices. An unauthenticated attacker can send specific SIP messages over TCP that cause the SIP headers to be parsed incorrectly, triggering a continuous loop. This loop leads to a watchdog timer expiration and crashes critical processes (flowd or mspmand), resulting in a denial of service.


How can this vulnerability impact me? :

The vulnerability can cause a denial of service (DoS) by crashing the flow management process on affected Junos OS devices. This crash disrupts normal network operations, potentially causing service outages or degraded network performance on SRX Series and MX Series devices with the specified service cards.


Ask Our AI Assistant
Need more information? Ask your question to get an AI reply (Powered by our expertise)
0/70
EPSS Chart