Improper Firewall Configuration in MR9600 and MX4200 Routers by Vendor
CVE-2026-27850

7.5HIGH

Key Information:

Vendor

Linksys
Status
Mr9600
Mx4200
Vendor
CVE Published:
25 February 2026

What is CVE-2026-27850?

A security vulnerability has been identified in specific router models where an improperly configured firewall rule allows unsolicited connections on the WAN port from the source port 5222. This flaw exposes services that are typically restricted to the local network, potentially allowing unauthorized access to sensitive data and functions. It is important for users of MR9600 and MX4200 routers to review their firewall settings to mitigate this risk.

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Affected Version(s)

MR9600 1.0.4.205530

MX4200 1.0.13.210200

References

https://www.syss.de/fileadmin/dokumente/Publikationen/Adv...
third-party-advisorytechnical-description

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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