CVE-2026-57026

Summary

An Improper Validation of Syntactic Correctness of Input vulnerability in the SIP plugin of Juniper Networks Junos OS on MX Series with SPC3 and SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).If the SIP ALG is enabled on an affected device, the processing of a malformed SIP invite packet will cause a flow processing daemon (flowd) crash and restart. This leads to a complete service outage until the system has automatically recovered.

This issue affects Junos OS on MX Series with SPC3 and SRX Series:

  • all versions before 23.2R2-S7,
  • 23.4 versions before 23.4R2-S8,
  • 24.2 versions before 24.2R2-S5,
  • 24.4 versions before 24.4R2-S4,
  • 25.2 versions before 25.2R2,
  • 25.4 versions before 25.4R1-S2.

Affected Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS0 < 23.2R2-S7affected
Juniper NetworksJunos OS23.4 < 23.4R2-S8affected
Juniper NetworksJunos OS24.2 < 24.2R2-S5affected
Juniper NetworksJunos OS24.4 < 24.4R2-S4affected
Juniper NetworksJunos OS25.2 < 25.2R2affected
Juniper NetworksJunos OS25.4 < 25.4R1-S2affected

Weaknesses

  • CWE-1286: CWE-1286 Improper Validation of Syntactic Correctness of Input

Workarounds

There are no known workarounds for this issue.

To reduce the risk of exploitation customers not requiring the SIP ALG functionality could explicitly disable it (in case it's by default enabled) by configuring:

[ security alg sip disable ]

References