Vulnerability · CVE-2021-35247
SolarWinds Serv-U Improper Input Validation Vulnerability
Published Jan 10, 2022 · corrected/updated Jun 16, 2026 · SolarWinds Serv-U · evidence confidence very high
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.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2021-35247 is a medium public vulnerability record for SolarWinds Serv-U. CISA lists it as known exploited. Published remediation guidance: Apply updates per vendor instructions. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether SolarWinds Serv-U is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: solarwinds/serv-u; SolarWinds Serv-U. Published remediation guidance: Apply updates per vendor instructions. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 5.3, EPSS 3.5%. CISA lists it as known exploited. Weakness classes: CWE-20. Sources contributing to this record: cisa_kev, cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Confirmed in CISA KEV since Jan 19, 2022. Listed in CISA KEV and VulnCheck KEV.
Patch and remediation
Apply updates per vendor instructions. CISA due date Feb 4, 2022.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Jan 10, 2022 · Catalog
Detected
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 schedu
Jan 21, 2022 · CISA KEV
Known exploited
Apply updates per vendor instructions.
Feb 4, 2022 · CISA KEV
Remediation due
Apply updates per vendor instructions.
Jun 16, 2026 · Catalog
Updated
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 schedu
Affected
- cpe solarwinds/serv-uversion unspecified
- vendor SolarWinds Serv-Uversion unspecified
Sources
- CISA KEVConfirmed exploitationCVE-2021-35247
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.
cisa.gov - CVE.orgVulnerability recordCVE-2021-35247
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2021-35247
30-day exploitation probability 3.5%
first.org - NIST NVDVulnerability recordCVE-2021-35247
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 ignor
nvd.nist.gov - VulnCheck KEVConfirmed exploitationCVE-2021-35247
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.
vulncheck.com