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CVE-2021-35247

Status: AnalyzedMedium (5.3)⚠ Active exploitation

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.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

CISA KEV — actively exploited

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

AV:N/AC:L/PR:N permite explotación remota sin autenticación (T1190). La sanitización insuficiente en LDAP podría permitir manipulación de datos de autenticación (T1565.002).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Vulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkFilter Network TrafficEncrypt Sensitive Information

Affected technologies (1)

Solarwinds — Serv-u

CWEs

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2021-35247",
  "cveTags": [],
  "metrics": {
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          "role": "CISA Coordinator",
          "options": [
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          "authentication": "NONE",
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  "published": "2022-01-10T14:10:17.667",
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    },
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      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35247",
      "tags": [
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  "weaknesses": [
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      "value": "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."
    },
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    }
  ],
  "lastModified": "2026-06-17T03:57:22.850",
  "cisaActionDue": "2022-02-04",
  "cisaExploitAdd": "2022-01-21",
  "configurations": [
    {
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  "sourceIdentifier": "psirt@solarwinds.com",
  "cisaRequiredAction": "Apply updates per vendor instructions.",
  "cisaVulnerabilityName": "SolarWinds Serv-U Improper Input Validation Vulnerability"
}