CVE-2021-34578 | WAGO: Authentication Vulnerability in Web-Based Management

This vulnerability allows an attacker who has access to the WBM to read and write settings-parameters of the device by sending specifically constructed requests without authentication on multiple WAGO PLCs in firmware versions up to FW07.

Published: 2021-08-31 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34578 is rated Moderate Risk (59.4/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.93%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-34578

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.32% 0.93% +0.61%
2 2025-03-30 0.68% 0.32% -0.35%
3 2025-03-29 — 0.68% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34578

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
8.1 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.9 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2021-34578

Affected software / configurations for CVE-2021-34578

Vendor Product Version Raw CPE
wago 750-890\/040-000_firmware <= fw07 cpe:2.3:o:wago:750-890\/040-000_firmware:*:*:*:*:*:*:*:*
wago 750-890\/025-001_firmware <= fw07 cpe:2.3:o:wago:750-890\/025-001_firmware:*:*:*:*:*:*:*:*
wago 750-890\/025-002_firmware <= fw07 cpe:2.3:o:wago:750-890\/025-002_firmware:*:*:*:*:*:*:*:*
wago 750-890\/025-000_firmware <= fw07 cpe:2.3:o:wago:750-890\/025-000_firmware:*:*:*:*:*:*:*:*
wago 750-832\/000-002_firmware <= fw07 cpe:2.3:o:wago:750-832\/000-002_firmware:*:*:*:*:*:*:*:*
wago 750-362_firmware <= fw07 cpe:2.3:o:wago:750-362_firmware:*:*:*:*:*:*:*:*
wago 750-823_firmware <= fw07 cpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*
wago 750-832_firmware <= fw07 cpe:2.3:o:wago:750-832_firmware:*:*:*:*:*:*:*:*
wago 750-363_firmware <= fw07 cpe:2.3:o:wago:750-363_firmware:*:*:*:*:*:*:*:*
wago 750-862_firmware <= fw07 cpe:2.3:o:wago:750-862_firmware:*:*:*:*:*:*:*:*
wago 750-891_firmware <= fw07 cpe:2.3:o:wago:750-891_firmware:*:*:*:*:*:*:*:*
wago 750-893_firmware <= fw07 cpe:2.3:o:wago:750-893_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-34578

cvelogic Threat Intelligence