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CVE-2026-22321— Stack-Based Buffer Overflow in CLI Login Username Handling over CLI

Quick assessment

Affected
Phoenix Contact FL SWITCH 2005
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

PHOENIX CONTACT FL SWITCH和PHOENIX CONTACT FL NAT都是德国菲尼克斯电气（PHOENIX CONTACT）公司的产品。PHOENIX CONTACT FL SWITCH是一款工业级以太网交换机。PHOENIX CONTACT FL NAT是一系列工业安全网关。 Phoenix Contact多款产品存在安全漏洞，该漏洞源于设备Telnet/SSH CLI登录例程中存在基于栈的缓冲区溢出，可能导致未经身份验证的攻击者造成线程崩溃，引发可用性中断。以下产品受到影响：

CVSS 5.3 · Medium EPSS 0.37% · P28

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-22321

Vulnerability Information
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Vulnerability Title
Stack-Based Buffer Overflow in CLI Login Username Handling over CLI
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
Phoenix Contact多款产品 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
PHOENIX CONTACT FL SWITCH和PHOENIX CONTACT FL NAT都是德国菲尼克斯电气（PHOENIX CONTACT）公司的产品。PHOENIX CONTACT FL SWITCH是一款工业级以太网交换机。PHOENIX CONTACT FL NAT是一系列工业安全网关。 Phoenix Contact多款产品存在安全漏洞，该漏洞源于设备Telnet/SSH CLI登录例程中存在基于栈的缓冲区溢出，可能导致未经身份验证的攻击者造成线程崩溃，引发可用性中断。以下产品受到影响：
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Phoenix Contact FL SWITCH 2005 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2008 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2016 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2105 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2108 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2116 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2204-2TC-2SFX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2205 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2FX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2FX SM 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2FX SM ST 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2FX ST 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2SFX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206-2SFX PN 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2206C-2FX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2207-FX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2207-FX SM 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2208 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2208 PN 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2208C 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2212-2TC-2SFX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2214-2FX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2214-2FX SM 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2214-2SFX 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2214-2SFX PN 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2216 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2216 PN 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2304-2GC-2SFP 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2306-2SFP 0.0.0 ~ 3.53 -
Phoenix Contact FL SWITCH 2306-2SFP PN 0.0.0 ~ 3.53 -

II. Public POCs for CVE-2026-22321

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III. Intelligence Information for CVE-2026-22321

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Vendor Advisories for CVE-2026-22321 (1)

Same Patch Batch · Phoenix Contact · 2026-03-18 · 8 CVEs total

CVE-2026-22317 7.2 HIGH Command Injection Vulnerability in Root CA Certificate Transfer Workflow
CVE-2026-22323 7.1 HIGH Cross‑Site Request Forgery in Link Aggregation Configuration
CVE-2026-22322 7.1 HIGH Stored Cross‑Site Scripting in Link Aggregation Name Handling
CVE-2026-22316 6.5 MEDIUM Buffer Overflow using TFTP Filename
CVE-2026-22320 6.5 MEDIUM Stack-Based Buffer Overflow in TFTP File-Transfer Command Handling over CLI
CVE-2026-22318 4.9 MEDIUM Stack-Based Buffer Overflow in File Transfer Parameter Handling
CVE-2026-22319 4.9 MEDIUM Stack-Based Buffer Overflow in File Install Parameter Handling

IV. Related Vulnerabilities

Same product: FL SWITCH 2005
Same vendor: Phoenix Contact
Same weakness: CWE-121

V. Comments for CVE-2026-22321

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