How severe is CVE-2021-33540?

CVE-2021-33540 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-33540 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33540?

CVE-2021-33540 primarily affects Phoenixcontact Axl F Bk Pn Tps Xc Firmware. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33540?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33540 published?

CVE-2021-33540 was published on 2021-06-25 and last updated on 2026-06-17.

CVE-2021-33540

CVE-2021-33540 is a high-severity vulnerability in Phoenixcontact Axl F Bk Pn Tps Xc Firmware with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-798.

Key facts

Severity: High (CVSS 3.x base score 7.3)
CVSS v2: 7.5
EPSS exploit prediction: 1% (50th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-798
Affected product: Phoenixcontact Axl F Bk Pn Tps Xc Firmware
Published: 2021-06-25
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-33540?: 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.
How severe is CVE-2021-33540?: CVE-2021-33540 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-33540 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (50th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33540?: CVE-2021-33540 primarily affects Phoenixcontact Axl F Bk Pn Tps Xc Firmware. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33540?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33540 published?: CVE-2021-33540 was published on 2021-06-25 and last updated on 2026-06-17.

References

https://cert.vde.com/en-us/advisories/vde-2021-021

Affected products (18)

cpe:2.3:o:phoenixcontact:axl_f_bk_pn_tps_xc_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_pn_tps_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_eip_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_eip_ef_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_eth_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_eth_xc_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_s35_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_pn_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_pn_xc_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_eth_net2_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:axl_f_bk_sas_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_pn_bk-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_pn_bk_di8_do4_2tx-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_pn_bk_di8_do4_2scrj-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_eth_bk_di8_do4_2tx-xc-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_eth_bk_di8_do4_2tx-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_eip_bk_di8_do4_2tx-pac_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:phoenixcontact:il_s3_bk_di8_do4_2tx-pac_firmware:*:*:*:*:*:*:*:*

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