Is CVE-2021-35247 actively exploited?

Yes. KEV Intelligence tracks CVE-2021-35247 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2021-35247. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-35247 affects SolarWinds Serv-U. Reported affected version: 15.2.5 and previous versions to < 15.3.

Yes. CVE-2021-35247 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2021-35247

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-35247 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Improper Input Validation Vulnerability in Serv-U

SolarWinds / Serv-U · affected before 15.3

View live feed Monitor via API Watch CVE

Severity: CVSS 4.3 · Medium
Confidence: Confirmed
Exploit status: Exploited in the wild
EPSS: 3.5%
First observed: —
Last observed: —

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-35247 is an unauthenticated Improper Input Validation Vulnerability in Serv-U. Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized. SolarWinds has...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

SolarWinds / Serv-U affected before 15.3.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Serv-U web login screen to LDAP authentication was allowing characters that were not sufficiently sanitized

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.

Vendor Product Affected Status

SolarWinds Serv-U Before 15.3 Affected

Published: 07 Jan 2022
Exploitation Reported: 21 Jan 2022
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: Required

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-35247
solarwinds.com/trust-center/security-advisories/cve-2021-35247 solarwinds.com · CVE Record https://www.solarwinds.com/trust-center/security-advisories/cve-2021-...
documentation.solarwinds.com/en/success_center/servu/content/release_note... documentation.solarwinds.com · CVE Record https://documentation.solarwinds.com/en/success_center/servu/content/...

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 21 Jan 2022

Independent exploitation attestation added to the KEV Intelligence record.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source	Added
CISA First	2022-01-21 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

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No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

4.3 Medium

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

EPSS

3.5%

Weaknesses

Improper Input Validation CWE-20

Timeline

From disclosure to observed exploitation

21 Jan 2022
Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
07 Jan 2022
CVE published

Vulnerability disclosed publicly
22 Jun 2021
CVE ID reserved

Identifier reserved by the CNA

Pro API

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-35247

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-35247",
  "confidence": "Confirmed",
  "cvss_score": 4.3,
  "cvss_estimated": false,
  "epss_score": 0.03453,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

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