Medium 4.3Known exploited (CISA KEV)Published Jan 7, 2022

CVE-2021-35247Improper Input Validation Vulnerability in Serv-U

Updated under an hour ago (2026-10-19 10:23 UTC)

Does this affect you?

It affects SolarWinds Serv-U and 1 other product. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Jan 21, 2022; federal agencies had to remediate by Feb 4, 2022. Treat that date as your deadline.

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Every CVE for SolarWinds Serv-U

Exploited in the last 30 days

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: 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-20
Known exploited: Added to CISA KEV Jan 21, 2022; federal remediation due Feb 4, 2022Apply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 3.45% (percentile 89)
Assigned by: SolarWinds
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

SolarWinds Serv-U solarwinds:serv_u (from the name)	from 15.2.5 and previous versions before 15.3	CNA record
solarwinds serv-u solarwinds:serv-u	before 15.3	NVD

References

https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35247x-refsource-misc, broken-link, vendor-advisory
https://documentation.solarwinds.com/en/success_center/servu/content/release_notes/servu_15-3_release_notes.htmx-refsource-misc, release-notes, vendor-advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35247us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.