CVE intelligence and bounded remediation

CVE-2021-33540 — Phoenixcontact Axl F Bk Pn Tps Xc Firmware security vulnerability

High CVSS 7.5

In certain devices of the Phoenix Contact AXL F BK and IL BK product families an undocumented password protected FTP access to the root directory exists.

Severity
High
CVSS
7.5 (2.0)
Published
2021-06-25
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-798

Affected products

  • phoenixcontact / axl_f_bk_pn_tps_xc_firmware
  • phoenixcontact / axl_f_bk_pn_tps_firmware
  • phoenixcontact / axl_f_bk_eip_firmware
  • phoenixcontact / axl_f_bk_eip_ef_firmware
  • phoenixcontact / axl_f_bk_eth_firmware
  • phoenixcontact / axl_f_bk_eth_xc_firmware

Showing 6 representative product identities from 18 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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