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Vulnerability · Published Mar 18, 2026 · Assigned by CERTVDE

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

Medium 5.3

In plain English

A medium-severity stack buffer overflow in FL SWITCH 2005 from Phoenix Contact. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.4%top 66.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

VendorProductVersions
Phoenix Contact FL SWITCH 2005 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2008 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2016 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2105 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2108 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2116 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2204-2TC-2SFX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2205 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2FX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2FX SM 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2FX SM ST 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2FX ST 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2SFX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206-2SFX PN 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2206C-2FX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2207-FX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2207-FX SM 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2208 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2208 PN 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2208C 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2212-2TC-2SFX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2214-2FX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2214-2FX SM 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2214-2SFX 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2214-2SFX PN 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2216 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2216 PN 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2304-2GC-2SFP 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2306-2SFP 0.0.0 – before 3.53
Phoenix Contact FL SWITCH 2306-2SFP PN 0.0.0 – before 3.53

Weakness: CWE-121 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References