CVE-2021-35247

Improper Input Validation Vulnerability in Serv-U

CVSS 3.1 Medium 4.3Known exploited (CISA KEV)

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Description

Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has updated the input mechanism to perform additional validation and sanitization. Please Note: No downstream affect has been detected as the LDAP servers ignored improper characters. To insure proper input validation is completed in all environments. SolarWinds recommends scheduling an update to the latest version of Serv-U.

Key data

CVSS 3.1 Medium 4.3

Score published by SolarWinds in the CVE record.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack vector: Network
The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity: Low
No special conditions are needed. The attack can be repeated at will.
Privileges required: None
No account or privileges are needed.
User interaction: Required
A user has to do something first, such as opening a file or following a link.
Scope: Unchanged
The impact stays within the vulnerable component.
Confidentiality impact: None
No effect on the secrecy of data.
Integrity impact: Low
Limited effect on the trustworthiness of data.
Availability impact: None
No effect on availability.

Metric	Value	What it means
Attack vector	Network	The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity	Low	No special conditions are needed. The attack can be repeated at will.
Privileges required	None	No account or privileges are needed.
User interaction	Required	A user has to do something first, such as opening a file or following a link.
Scope	Unchanged	The impact stays within the vulnerable component.
Confidentiality impact	None	No effect on the secrecy of data.
Integrity impact	Low	Limited effect on the trustworthiness of data.
Availability impact	None	No effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score: 0.03642 (3.6% probability)
Percentile: 89.7%
Scores of: Nov 10, 2026
Model: v2026.06.15

CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.

Name in the catalog: SolarWinds Serv-U Improper Input Validation Vulnerability
Added to the catalog: Jan 21, 2022
Federal due date: Feb 4, 2022

CISA assessment as of Jan 29, 2025

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Exploitation: Recorded by CISA as active
Automatable: no
Technical impact: partial

Weakness (CWE)

CWE catalog version 5.0.

CWE-20Improper Input Validation

Affected products

Products listed in the CVE record, as the CNA published them.

SolarWinds Serv-U
- affected: 15.2.5 and previous versions up to before 15.3

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

ID reservedJun 22, 2021
Record publishedJan 7, 2022
Added to CISA KEVJan 21, 2022
Record last updatedOct 21, 2025

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About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:33 UTC. Sources and licenses