CVE-2021-35247: SolarWinds Serv-U Improper Input Validation Vulnerability

CISA Known Exploited Vulnerabilities

Name

SolarWinds Serv-U Improper Input Validation Vulnerability

Vendor

SolarWinds

Product

Serv-U

Added to the catalog

2022-01-21

Due date for US federal agencies

2022-02-04

Weaknesses

CWE-20

Catalog version

2026.10.30

SolarWinds Serv-U versions 15.2.5 and earlier contain an improper input validation vulnerability that allows attackers to build and send queries without sanitization.

Required action (CISA)

Apply updates per vendor instructions.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

• https://nvd.nist.gov/vuln/detail/CVE-2021-35247

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status

Analyzed

Published

2022-01-10T14:10:17.667

Last modified

2026-06-17T03:57:22.850

Weaknesses

CWE-20, NVD-CWE-noinfo

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.

References

• https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm (Release Notes, Vendor Advisory)
• https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247 (Broken Link, Vendor Advisory)
• https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm (Release Notes, Vendor Advisory)
• https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247 (Broken Link, Vendor Advisory)
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35247 (US Government Resource)

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:59.479Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-35247

CVE record

Title (CNA)

Improper Input Validation Vulnerability in Serv-U

Assigner

SolarWinds

State

PUBLISHED

Published

2022-01-07T22:39:50.564Z

Updated

2025-10-21T23:15:49.752Z

Problem types

CWE-20 Improper Input Validation

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.

References

• https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247
• https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htm

Read on 2026-11-03T01:08:18.438Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2021/35xxx/CVE-2021-35247.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

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