How severe is CVE-2021-20998?

CVE-2021-20998 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20998 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20998?

CVE-2021-20998 primarily affects Wago 0852-0303 Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20998?

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

When was CVE-2021-20998 published?

CVE-2021-20998 was published on 2021-05-13 and last updated on 2026-06-17.

CVE-2021-20998

CVE-2021-20998 is a critical-severity vulnerability in Wago 0852-0303 Firmware with a CVSS 3.x base score of 10.0. 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-306.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
CVSS v2: 7.5
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-306
Affected product: Wago 0852-0303 Firmware
Published: 2021-05-13
Last modified: 2026-06-17

Description

In multiple managed switches by WAGO in different versions without authorization and with specially crafted packets it is possible to create users.

Frequently asked questions

What is CVE-2021-20998?: In multiple managed switches by WAGO in different versions without authorization and with specially crafted packets it is possible to create users.
How severe is CVE-2021-20998?: CVE-2021-20998 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20998 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20998?: CVE-2021-20998 primarily affects Wago 0852-0303 Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20998?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-20998 published?: CVE-2021-20998 was published on 2021-05-13 and last updated on 2026-06-17.

References

https://cert.vde.com/en-us/advisories/vde-2021-013

Affected products (5)

cpe:2.3:o:wago:0852-0303_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:0852-1305_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:0852-1505_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:0852-1305\/000-001_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:wago:0852-1505\/000-001_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Wago 0852-0303 Firmware

CVE-2021-20994 — High (CVSS 8.8): In multiple managed switches by WAGO in different versions an attacker may trick a legitimate user to click a link to…
CVE-2021-20997 — High (CVSS 7.5): In multiple managed switches by WAGO in different versions it is possible to read out the password hashes of all…
CVE-2021-20996 — Medium (CVSS 5.3): In multiple managed switches by WAGO in different versions special crafted requests can lead to cookies being…
CVE-2021-20995 — Medium (CVSS 5.3): In multiple managed switches by WAGO in different versions the webserver cookies of the web based UI contain user…
CVE-2021-20993 — Medium (CVSS 5.3): In multiple managed switches by WAGO in different versions the activated directory listing provides an attacker with…

All CVEs affecting Wago 0852-0303 Firmware →

Other CWE-306 (Missing Authentication for Critical Function) vulnerabilities

CVE-2026-63692 — Critical (CVSS 10.0): Dell Container Storage Modules, versions prior to 1.18.0, contain(s) a Missing Authentication for Critical Function…
CVE-2026-63688 — Critical (CVSS 10.0): Dell Container Storage Modules (CSM), versions prior to v1.18.0, contains a Missing Authentication for Critical…
CVE-2026-103956 — Critical (CVSS 10.0): Missing authentication for critical function in the authentication dependency in Loom for AWS before 1.6.1 allowed…
CVE-2026-53988 — Critical (CVSS 10.0): Dockhand before 1.0.40 contains an authentication bypass vulnerability in its git webhook endpoints that allows…
CVE-2026-85889 — Critical (CVSS 10.0): Missing authentication for critical function in Azure AI Foundry allows an unauthorized attacker to elevate privileges…
CVE-2026-92808 — Critical (CVSS 10.0): A server-side request forgery (SSRF) vulnerability exists in the UnifiedLogin service of Altium Enterprise Server. An…

Browse all CWE-306 (Missing Authentication for Critical Function) vulnerabilities →