Riskcovery

CVE-2026-21905

Junos OS: SRX Series, MX Series with MX-SPC3 or MS-MPC: Receipt of multiple specific SIP messages results in flow management process crash

State
Published
Severity
8.7 High
Published
Jan 15, 2026
Updated
Jan 16, 2026
Reserved
Jan 5, 2026

Read the record on cve.org

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,  * 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.

Scores

CVSSScoreVectorSource
4.08.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amberjuniper
3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hjuniper

Weaknesses

  • CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

Affected Products

ProductVersions
Junos OSJuniper Networks
  • before 21.2R3-S10Affected
  • 21.4 to before 21.4R3-S12Affected
  • 22.4 to before 22.4R3-S8Affected
  • 23.2 to before 23.2R2-S5Affected
  • 23.4 to before 23.4R2-S6Affected
  • 24.2 to before 24.2R2-S3Affected
  • 24.4 to before 24.4R2-S1Affected
  • 25.2 to before 25.2R1-S1, 25.2R2Affected

References

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