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High severity7.5NVD Advisory· Published Jan 15, 2026· Updated Jun 17, 2026

CVE-2026-21905

CVE-2026-21905

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.

Affected products

88
  • Juniper Networks/Junos88 versions
    cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*+ 87 more
    • cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*range: <21.2
    • cpe:2.3:o:juniper:junos:21.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s6:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s7:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s8:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3-s9:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.2:r3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s10:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s11:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s6:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s7:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s8:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3-s9:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:21.4:r3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s6:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3-s7:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s4:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2-s5:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r2-s1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r2-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.2:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.4:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:24.4:r2:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:25.2:-:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:25.2:r1:*:*:*:*:*:*
    • cpe:2.3:o:juniper:junos:25.2:r2:*:*:*:*:*:*
    • (no CPE)range: 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
    • (no CPE)range: 0

Patches

Vulnerability mechanics

References

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News mentions

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