How severe is CVE-2021-35223?

CVE-2021-35223 has a CVSS 3.x base score of 8.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-35223 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35223?

CVE-2021-35223 affects Solarwinds Serv-u. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35223?

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-2021-35223 published?

CVE-2021-35223 was published on 2021-08-31 and last updated on 2026-06-17.

CVE-2021-35223

CVE-2021-35223 is a high-severity vulnerability in Solarwinds Serv-u with a CVSS 3.x base score of 8.5. 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-20.

Key facts

Severity: High (CVSS 3.x base score 8.5)
CVSS v2: 6.5
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Solarwinds Serv-u
Published: 2021-08-31
Last modified: 2026-06-17

Description

The Serv-U File Server allows for events such as user login failures to be audited by executing a command. This command can be supplied with parameters that can take the form of user string variables, allowing remote code execution.

Frequently asked questions

What is CVE-2021-35223?: The Serv-U File Server allows for events such as user login failures to be audited by executing a command. This command can be supplied with parameters that can take the form of user string variables, allowing remote code execution.
How severe is CVE-2021-35223?: CVE-2021-35223 has a CVSS 3.x base score of 8.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-35223 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35223?: CVE-2021-35223 affects Solarwinds Serv-u. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35223?: 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-2021-35223 published?: CVE-2021-35223 was published on 2021-08-31 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:solarwinds:serv-u:*:*:*:*:*:*:*:*

More vulnerabilities in Solarwinds Serv-u

CVE-2020-35481 — Critical (CVSS 9.8): SolarWinds Serv-U before 15.2.2 allows Unauthenticated Macro Injection.
CVE-2025-40541 — Critical (CVSS 9.1): An Insecure Direct Object Reference (IDOR) vulnerability exists in Serv-U, which when exploited, gives a malicious…
CVE-2025-40540 — Critical (CVSS 9.1): A type confusion vulnerability exists in Serv-U which when exploited, gives a malicious actor the ability to execute…
CVE-2025-40539 — Critical (CVSS 9.1): A type confusion vulnerability exists in Serv-U which when exploited, gives a malicious actor the ability to execute…
CVE-2025-40538 — Critical (CVSS 9.1): A broken access control vulnerability exists in Serv-U which when exploited, gives a malicious actor the ability to…
CVE-2025-40549 — Critical (CVSS 9.1): A Path Restriction Bypass vulnerability exists in Serv-U that when abused, could give a malicious actor with access to…

All CVEs affecting Solarwinds Serv-u →

Other CWE-20 (Improper Input Validation) vulnerabilities

CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →