Stack-Based Buffer Overflow in Telnet/SSH CLI for Device
CVE-2026-22321

5.3MEDIUM

Key Information:

Vendor

Phoenix Contact

Status
Fl Switch 2005
Fl Switch 2008
Fl Switch 2016
Fl Switch 2105
Vendor
CVE Published:
18 March 2026

What is CVE-2026-22321?

A stack-based buffer overflow vulnerability exists in the Telnet/SSH command-line interface (CLI) login routine of certain devices. This flaw allows an unauthenticated attacker to send oversized or unexpected username input, leading to an overflow condition that disrupts the login process. Although this results in a crash of the thread handling the login attempt, it does not affect other active CLI sessions. As a consequence, the impact is characterized by a limited availability disruption.

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Affected Version(s)

FL NAT 2008 0.0.0 < 3.53

FL NAT 2208 0.0.0 < 3.53

FL NAT 2304-2GC-2SFP 0.0.0 < 3.53

References

https://certvde.com/de/advisories/VDE-2025-104

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Gabriele Quagliarella from Nozomi Networks
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