CVE-2026-22321

Stack-Based Buffer Overflow in CLI Login Username Handling over CLI

5.3 Medium

A stack-based buffer overflow in the device's Telnet/SSH CLI login routine occurs when a unauthenticated attacker send an oversized or unexpected username input. An overflow condition crashes the thread handling the login attempt, forcing the session to close. Because other CLI sessions remain unaffected, the impact is limited to a low‑severity availability disruption.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: Low

Exploit likelihood

0.39%Up 0.4 points since Mar 18, 2026

What each source reports

CVE List Score used 5.3

Stack-Based Buffer Overflow in CLI Login Username Handling over CLI

Record: CVE-2026-22321
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-121
Updated: 2026-11-02

EUVDEUVD-2026-12790 5.3

Record: EUVD-2026-12790
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated: 2026-11-02

GitHub AdvisoriesGHSA-j66g-mfcw-hrf3 5.3

A stack-based buffer overflow in the device's Telnet/SSH CLI login routine occurs when a...

Record: GHSA-j66g-mfcw-hrf3
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-121
Updated: 2026-11-02

NVD 5.3

Record: CVE-2026-22321
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-121
Updated: 2026-11-02

Affected products

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History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-22321 is a medium vulnerability (CVSS 5.3) in Phoenix Contact Fl Nat 2008, published March 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. No source names a fixed version.